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Saunthwal RK, Mortimer J, Orr-Ewing AJ, Clayden J. Enantioselective one-carbon expansion of aromatic rings by simultaneous formation and chromoselective irradiation of a transient coloured enolate. Chem Sci 2022; 13:2079-2085. [PMID: 35308841 PMCID: PMC8848985 DOI: 10.1039/d1sc06684f] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/25/2022] [Indexed: 12/14/2022] Open
Abstract
Enantioenriched seven-membered carbocycles are motifs in many molecules of structural and biological interest. We report a simple, practical, transition metal-free and mechanistically unusual method for the enantioselective synthesis of substituted cycloheptatrienes. By forming a coloured enolate with an appropriate absorption band and selectively irradiating in situ, we to initiate a tandem, asymmetric anionic and photochemical ring expansion of readily accessible N-benzylbenzamides. The cascade of reactions leading to the products entails enantioselective benzylic deprotonation with a chiral lithium amide, dearomatizing cyclization of the resulting configurationally defined organolithium to give an extended amide enolate, and photochemically induced formal [1,7]-sigmatropic rearrangement and 6π-electrocyclic ring-opening - the latter all evidently being stereospecific - to deliver enantioenriched cycloheptatrienes with embedded benzylic stereocentres.
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Affiliation(s)
- Rakesh K Saunthwal
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - James Mortimer
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Jonathan Clayden
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
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2
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Eagling L, Leonard DJ, Schwarz M, Urruzuno I, Boden G, Wailes JS, Ward JW, Clayden J. 'Reverse biomimetic' synthesis of l-arogenate and its stabilized analogues from l-tyrosine. Chem Sci 2021; 12:11394-11398. [PMID: 34667547 PMCID: PMC8447241 DOI: 10.1039/d1sc03554a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/12/2021] [Indexed: 11/21/2022] Open
Abstract
l-Arogenate (also known as l-pretyrosine) is a primary metabolite on a branch of the shikimate biosynthetic pathway to aromatic amino acids. It plays a key role in the synthesis of plant secondary metabolites including alkaloids and the phenylpropanoids that are the key to carbon fixation. Yet understanding the control of arogenate metabolism has been hampered by its extreme instability and the lack of a versatile synthetic route to arogenate and its analogues. We now report a practical synthesis of l-arogenate in seven steps from O-benzyl l-tyrosine methyl ester in an overall yield of 20%. The synthetic route also delivers the fungal metabolite spiroarogenate, as well as a range of stable saturated and substituted analogues of arogenate. The key step in the synthesis is a carboxylative dearomatization by intramolecular electrophilic capture of tyrosine's phenolic ring using an N-chloroformylimidazolidinone moiety, generating a versatile, functionalizable spirodienone intermediate. l-Tyrosine provides a precursor for a practical synthesis of the unstable primary metabolite l-arogenate and some stabilised arogenate analogues.![]()
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Affiliation(s)
- Louise Eagling
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Daniel J Leonard
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Maria Schwarz
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Iñaki Urruzuno
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Grace Boden
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - J Steven Wailes
- Jealott's Hill International Research Centre Bracknell RG42 6EY UK
| | - John W Ward
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Jonathan Clayden
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
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4
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A compendium of cyclic sugar amino acids and their carbocyclic and heterocyclic nitrogen analogues. Amino Acids 2013; 45:613-89. [DOI: 10.1007/s00726-013-1521-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/21/2013] [Indexed: 12/19/2022]
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5
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Dearomatising cyclisation of lithiated allyl phenyl ethers: the role of an oxazoline substituent. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2013.05.098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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Senczyszyn J, Brice H, Clayden J. Spirocyclic Dihydropyridines by Electrophile-Induced Dearomatizing Cyclization of N-Alkenyl Pyridinecarboxamides. Org Lett 2013; 15:1922-5. [DOI: 10.1021/ol400571j] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Jemma Senczyszyn
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Heloise Brice
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Jonathan Clayden
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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Lemière G, Sedehizadeh S, Toueg J, Fleary-Roberts N, Clayden J. A general synthetic approach to the amnesic shellfish toxins: total synthesis of (−)-isodomoic acid B, (−)-isodomoic acid E and (−)-isodomoic acid F. Chem Commun (Camb) 2011; 47:3745-7. [DOI: 10.1039/c1cc00048a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Brice H, Clayden J, Hamilton SD. Fused bicyclic piperidines and dihydropyridines by dearomatising cyclisation of the enolates of nicotinyl-substituted esters and ketones. Beilstein J Org Chem 2010; 6:22. [PMID: 20502604 PMCID: PMC2874404 DOI: 10.3762/bjoc.6.22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 02/11/2010] [Indexed: 11/23/2022] Open
Abstract
The silyl enol ether derivatives of ketones or esters tethered by a hydrocarbon or ether linkage to the 3-position of a pyridine ring undergo dearomatising nucleophilic attack on the ring once it is activated (as an acylpyridinium species) by the addition of methyl chloroformate. The bicyclic dihydropyridine products are in some cases unstable, but may be isolated after hydrogenation as fused bicyclic piperidines.
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Affiliation(s)
- Heloise Brice
- School of Chemistry, University of Manchester, Oxford Rd., Manchester M13 9PL, United Kingdom
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9
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Brice H, Clayden J. Doubly dearomatising intramolecular coupling of a nucleophilic and an electrophilic heterocycle. Chem Commun (Camb) 2009:1964-6. [DOI: 10.1039/b901558b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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10
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Arnott G, Brice H, Clayden J, Blaney E. Electrophile-induced dearomatizing spirocyclization of N-arylisonicotinamides: a route to spirocyclic piperidines. Org Lett 2008; 10:3089-92. [PMID: 18553971 DOI: 10.1021/ol801092s] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Treatment of N-arylisonicotinamides with trifluoromethanesulfonic anhydride triggers intramolecular nucleophilic attack of the aryl ring on the 4-position of the pyridinium intermediate. The products are spirocyclic dihydropyridines which can be converted to valuable spirocyclic piperidines related to biologically active molecules such as MK-677.
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Affiliation(s)
- Gareth Arnott
- School of Chemistry, University of Manchester, Manchester, UK
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11
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Ruiz-Gómez G, Iglesias MJ, Serrano-Ruiz M, López-Ortiz F. Dearomatizing anionic cyclization of N-alkyl-N-benzyl(dinaphthyl)phosphinamides. A facile route to gamma-(amino)dihydronaphthalenylphosphinic acids. J Org Chem 2007; 72:9704-12. [PMID: 17979287 DOI: 10.1021/jo701607s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dearomatizing anionic cyclization of N-alkyl-N-benzyldi(n-naphthyl)phosphinamides (n = 1, 2) and subsequent trapping with a series of electrophiles (MeOH, MeI, CF3SO3Me, Me3O+BF4-, AllylBr, and PhCH2Br) have been accomplished. Optimized reaction conditions (base, temperature, reaction time) allow for synthesizing tetrahydro-1H-naphtho[1,2-c][1,2]-azaphosphole 1-oxides 13 and 18 and tetrahydro-1H-naphtho[2,1-c][1,2]azaphosphole 3-oxides 16 and 27-29 in high yield and diastereoselectivity. Appropriate selection of the base proved to be critical for promoting anionic cyclization of 2-naphthyl derivatives. The dearomatized heterocycles are transformed quantitatively into gamma-(N-alkylamino)phosphinic acids by acid hydrolysis of the P-N linkage. Bioactivity assays on five human tumor cell lines for one of these amino acids revealed growth inhibition factors (GI50) at a micromolar scale. Additionally, evidence for the feasibility of intermolecular nucleophilic dearomatization and sequential nucleophilic attack to both aromatic rings of dinaphthylphosphinamides have been obtained.
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Affiliation(s)
- Gloria Ruiz-Gómez
- Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento, 04120 Almería, Spain
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12
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Chiou WH, Schoenfelder A, Sun L, Mann A, Ojima I. Rhodium-Catalyzed Cyclohydrocarbonylation Approach to the Syntheses of Enantiopure Homokainoids. J Org Chem 2007; 72:9418-25. [DOI: 10.1021/jo070942n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wen-Hua Chiou
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Faculté de Pharmacie, Laboratoire de Pharmacochimie de la Communication Cellulaire UMR 7081, 67401 Illkirch, France
| | - Angèle Schoenfelder
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Faculté de Pharmacie, Laboratoire de Pharmacochimie de la Communication Cellulaire UMR 7081, 67401 Illkirch, France
| | - Liang Sun
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Faculté de Pharmacie, Laboratoire de Pharmacochimie de la Communication Cellulaire UMR 7081, 67401 Illkirch, France
| | - André Mann
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Faculté de Pharmacie, Laboratoire de Pharmacochimie de la Communication Cellulaire UMR 7081, 67401 Illkirch, France
| | - Iwao Ojima
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, and Faculté de Pharmacie, Laboratoire de Pharmacochimie de la Communication Cellulaire UMR 7081, 67401 Illkirch, France
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13
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Oxidative fragmentation of bicyclic hydroxy silanes and stannanes: a strategy for the stereoselective synthesis of kainoids. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.09.150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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da Silva KP, Godoi MN, Correia CRD. Regio- and Stereoselective Heck Arylations of N-Carbomethoxy-l- 3-Dehydroproline Methyl Ester with Arenediazonium Salts. Total Synthesis of Neuroexcitatory Aryl Kainoids. Org Lett 2007; 9:2815-8. [PMID: 17590003 DOI: 10.1021/ol070980t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Heck arylation of N-carbomethoxy-L-3-dehydroproline methyl ester with arenediazonium tetrafluoroborates produced chiral 4-aryldehydroproline derivatives in moderate to good yields in a highly regio- and stereocontrolled fashion. A rationale for the unexpected high regioselectivity is provided using Deeth's model. Heck adduct 15 (G = o-CH3O) was converted into several aryl kainoids using concise and efficient routes.
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Affiliation(s)
- Kezia Peixoto da Silva
- Instituto de Química, Universidade Estadual de Campinas, UNICAMP, C.P. 6154, 13084-971, Campinas, São Paulo, Brazil
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Paryzek Z, Skiera I. SYNTHESIS AND CLEAVAGE OF LACTONES AND THIOLACTONES. APPLICATIONS IN ORGANIC SYNTHESIS. A REVIEW. ORG PREP PROCED INT 2007. [DOI: 10.1080/00304940709356015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Ortiz FL, Iglesias MJ, Fernandez I, Sanchez CMA, Gómez GR. Nucleophilic Dearomatizing (DNAr) Reactions of Aromatic C,H-Systems. A Mature Paradigm in Organic Synthesis. Chem Rev 2007; 107:1580-691. [PMID: 17488057 DOI: 10.1021/cr030207l] [Citation(s) in RCA: 266] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fernando López Ortiz
- Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento s/n, 04120 Almería, Spain.
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17
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Arnott G, Clayden J, Hamilton SD. Azabicyclic amino acids by stereoselective dearomatizing cyclization of the enolates of N-nicotinoyl glycine derivatives. Org Lett 2007; 8:5325-8. [PMID: 17078709 DOI: 10.1021/ol062126s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[Structure: see text] On activation by pyridine N-acylation, enolates of N-nicotinoyl and N-isonicotinoyl glycine and alanine derivatives cyclize to yield 6,5-azabicyclic or 6,4-azaspirocyclic lactams. With an N-alpha-methyl-p-methoxybenzyl group the cyclization is diastereoselective; hydrogenation and deprotection yields azabicyclic amino acids in 94:6 er.
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Affiliation(s)
- Gareth Arnott
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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18
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Derdau V, Atzrodt J, Markó IE, Harwood SJ, Moenius T, Salter R, Wietfeld B, Burtscher P, Zueger C, Clayden J, Salter R, Bordeaux K, Burtscher P, Metz Y, Moenius T, Rodriguez I, Ruetsch R, Voges R, Zueger C, Gardiner JM, Stimpson W, Panchal N, Herbert J, Ellames GJ, Beller M, Kozempel J, Kadeřávek J, Lešetický L, Lebeda O, Wähälä K, Kiuru P, Leppälä E, Pohjoispää M, Parikka K, Raffaelli B, Herbert JM, Janssen CGM, Verluyten WLM, Vliegen M, Mäding P, Füchtner F, Bergmann R, Pietzsch J, Hultsch C, Wüst F, Scheunemann M, Vercouillie J, Fischer S, Sorger D, Großmann U, Schliebs R, Sabri O, Steinbach J. 13th Workshop of the Central European Division e.V. of the International Isotope Society. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.1020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ramallal AM, Fernández I, López Ortiz F, González J. Mechanism of Anionic Dearomatizing Reactions of Diphenylphosphinamide Derivatives: A Theoretical and Experimental Study. Chemistry 2005; 11:3022-31. [PMID: 15761841 DOI: 10.1002/chem.200400987] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The mechanism of the anionic dearomatisation of phosphinamide derivatives has been investigated both theoretically and experimentally. The potential-energy surface of model reactions was studied at the Becke3LYP/6-31+G* level of theory, and according to this study, a pre-reactive complex is formed between the alkyllithium and the phosphinamide. This complex evolves preferentially through NC(alpha)-metalation of the phosphinamide. The intramolecular nucleophilic addition of the carbanion to the ortho position of the aromatic ring leads to the dearomatised products, in a reaction that has been shown to be under thermodynamic control. Coordinating co-solvents, such as hexamethyl phosphoramide (HMPA) or N,N'-dimethyl-N,N'-propylene urea (DMPU), appear to influence the reaction by favouring the formation of solvent-separated ion pairs. The cyclisation reaction of allylphosphinamide derivatives was also studied. It was found that both the alpha- and gamma-attack of the allyl anion can take place, however the formation of the seven-membered ring products derived from the gamma-attack are clearly favoured.
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Affiliation(s)
- Antonio Morán Ramallal
- Departamento de Química Orgánica e Inorgánica, Universidad de Oviedo c/Julián Clavería 8, 33006 Oviedo, Spain
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Fernández I, González J, López-Ortiz F. Deuterium-Labeling and NMR Study of the Dearomatization of N-Alkyl-N-benzyldiphenylphosphinamides through Anionic Cyclization: Ortho and Benzylic Lithiation Directed by Complex-Induced Proximity Effects. J Am Chem Soc 2004; 126:12551-64. [PMID: 15453788 DOI: 10.1021/ja039863t] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism of the anionic cyclization dearomatizing reaction of N-benzyl-N-methyldiphenylphosphinamide (1) upon treatment with s-BuLi in tetrahydrofuran (THF) at -90 degrees C has been analyzed by deuterium-labeling and natural abundance multinuclear magnetic resonance ((1)H, (2)H, (7)Li, (13)C, (31)P) studies. In the absence of coordinating cosolvents such as hexamethylphosphoramide (HMPA), eight major anionic species were identified, which allowed us to unravel the pathway of the metalation reaction. In agreement with the complex-induced proximity effect (CIPE) mechanism, the sequence of transformations emerging from this study involves the coordination of the lithium base to the P=O group of 1 to give four dimeric precomplexes whose NMR data are consistent with structures Va/Vb and VIIIa/VIIIb. The diastereomers Va/Vb are the precursors of the monomeric benzylic anion II, whereas the VIIIa/VIIIb diastereomers are assumed to undergo ortho deprotonation leading to anions I. Translocation from the ortho anion to the benzylic one is not observed. Intramolecular conjugate addition of anion II to the P-phenyl rings happens in a reversible way, affording the monomeric dearomatized anions III, IV, VI, and VII. The reaction progresses to yield a mixture containing only the species I, III, and IV. HMPA acts as a catalyst for the ortho-to-benzylic translocation and anionic cyclization reactions. Two-dimensional (2D) (7)Li,(31)P[(1)H] shift correlations and (7)Li[(31)P] NMR spectra proved to be crucial for the structural assignment of the anionic species. These techniques also demonstrated the diastereotopicity of the two achiral ligands involved in a dimer with s-BuLi (Vb) owing to the slow configuration inversion of the carbanion center.
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Affiliation(s)
- Ignacio Fernández
- Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento s/n, Almería, Spain
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Ji T, Lee M, Pruitt SC, Hangauer DG. Privileged scaffolds for blocking protein-protein interactions: 1,4-disubstituted naphthalene antagonists of transcription factor complex HOX-PBX/DNA. Bioorg Med Chem Lett 2004; 14:3875-9. [PMID: 15225688 DOI: 10.1016/j.bmcl.2004.05.068] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Revised: 05/26/2004] [Accepted: 05/27/2004] [Indexed: 11/21/2022]
Abstract
Structure-based-design studies, with the crystal structure of the HOXB1-PBX1/DNA transcription factor complex, were used to identify 1,4-disubstituted naphthalenes as potential antagonists. An initial library of 32 analogs was synthesized, two of which were found to be more potent than the reported activity for a 12 amino acid peptide antagonist. Antagonists were also identified of the related BRN1/DNA and BRN2/DNA transcription factor complexes indicating that a 1,4-disubstituted naphthalene may be a privileged scaffold for preparing screening libraries targeting this family of transcription factor complexes.
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Affiliation(s)
- Tao Ji
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY 14260-3000, USA
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Fernández I, Forcén-Acebal A, García-Granda S, López-Ortiz F. Synthesis of functionalized 1,4-cyclohexadienes through intramolecular anionic dearomatization of N-alkyl-N-benzyldiphenylphosphinamides. Insight into the reaction mechanism. J Org Chem 2003; 68:4472-85. [PMID: 12762753 DOI: 10.1021/jo0342370] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A generalization of the intramolecular nucleophilic dearomatization-electrophilic alkylation reactions of N-alkyl-N-benzyldiphenylphosphinamide anions is presented. The process has been optimized by analyzing the effects of metalation and quench times, additives, the nature of the electrophiles used (MeI, CF(3)SO(3)Me, Me(3)O(+)BF(4)(-), AllylBr, PhCH(2)Br, BrCH(2)CO(2)Me, and RCH=O, where R = Ph, 4-Cl-C(6)H(4), 4-MeO-C(6)H(4), and (i)()Pr), and the alkyl substituent linked to the nitrogen of the phosphinamide. Both HMPA and DMPU act as catalysts. The latter proved to be much more efficient for obtaining high yields of substituted tetrahydrobenzo[c][1,2]-1lambda(5)-phospholes containing a 1,4-cyclohexadiene system with very high regio- and diastereoselectivity. Steric effects in the neighborhood of the benzylic anion tend to decrease the stereoselectivity of the anionic cyclization. The optimization study also served to shed light on the reaction mechanism of the dearomatization process by identifying several intermediate species and showing the reversibility of the anionic cyclization step as well as of the reaction with aldehydes.
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Affiliation(s)
- Ignacio Fernández
- Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento, Spain
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Sun PP, Chang MY, Chiang MY, Chang NC. A facile route to polysubstitutedN-benzyl pyroglutamates. Org Lett 2003; 5:1761-3. [PMID: 12735771 DOI: 10.1021/ol0344164] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Base-induced coupling/cyclization reactions of alpha-sulfonylacetamide with various ethyl (Z)-2-bromo-2-propenoates have been carried out. The polysubstituted pyroglutamate carbon skeleton, with three contiguous asymmetric centers, was built up in one step. A ring-closure mechanism is proposed for the reactions.
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Affiliation(s)
- Pei-Pei Sun
- Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
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Clayden J, Knowles FE, Menet CJ. Synthesis of α-methyl kainic acid by stereospecific lithiation–dearomatizing cyclization of a chiral benzamide. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(03)00570-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Clayden J, Menet CJ. 2,3-Dihydroisoindolones by cyclisation and rearomatisation of lithiated benzamides. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(03)00545-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Clayden J, Menet CJ, Tchabanenko K. Synthesis of (−)-kainic acid using chiral lithium amides in an asymmetric dearomatizing cyclization. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00379-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Fernández I, Ortiz FL, Velázquez AM, Granda SG. Regio- and diastereoselective preparation of tetrahydrobenzo[c]-1-aza-2lambda(5)-phospholes through dearomatization cyclization of lithiated N-benzyl-N-alkyl(diphenyl)phosphinamides. Synthesis of gamma-(N-alkylamino)phosphinic acids. J Org Chem 2002; 67:3852-60. [PMID: 12027703 DOI: 10.1021/jo025587+] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A study of the protonation of the cycloadducts derived from the dearomatization reaction of lithiated N-alkyl-N-benzyldiphenylphosphinamides has been carried out. The regio- and stereoselectivity of the process has been analyzed in terms of the size of the N-alkyl substituent, the acidity and size of the protonating reagent, and the cosolvent used. The optimization of these variables allowed the preparation of tetrahydrobenzo[c]-1-aza-2lambda(5)-phospholes containing a 1,3-cyclohexadiene or 1,4-cyclohexadiene system with moderate to excellent regio- and stereocontrol. The heterocycles were readily hydrolyzed, affording gamma-(N-alkylamino)diphenylphosphinic acids with the functionalities linked to a cyclohexadiene substructure.
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Affiliation(s)
- Ignacio Fernández
- Area de Química Orgánica, Universidad de Almería, Carretera de Sacramento, 04120 Almería, Spain
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Andújar Sánchez CM, Iglesias MJ, López Ortiz F. Dearomatisation of 1- and 2-cyanonaphthalene through nucleophilic conjugate addition. Tetrahedron Lett 2002. [DOI: 10.1016/s0040-4039(02)00316-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Clayden J, Purewal S, Helliwell M, Mantell SJ. Dearomatizing disrotatory electrocyclic ring closure of lithiated N-benzoyloxazolidines. Angew Chem Int Ed Engl 2002; 41:1049-51. [PMID: 12491309 DOI: 10.1002/1521-3773(20020315)41:6<1049::aid-anie1049>3.0.co;2-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jonathan Clayden
- Department of Chemistry, University of Manchester, Oxford Rd, Manchester M13 9PL, UK.
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Clayden J, Purewal S, Helliwell M, Mantell SJ. Dearomatizing Disrotatory Electrocyclic Ring Closure of LithiatedN-Benzoyloxazolidines. Angew Chem Int Ed Engl 2002. [DOI: 10.1002/1521-3757(20020315)114:6<1091::aid-ange1091>3.0.co;2-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bragg RA, Clayden J, Menet CJ. ‘meso-Selective’ functionalisation of N-benzyl-α-methylbenzylamine derivatives by α-lithiation and alkylation. Tetrahedron Lett 2002. [DOI: 10.1016/s0040-4039(02)00154-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Regio- and Stereoselective Addition Reactions of Organolithiums. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1460-1567(02)80038-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Bragg RA, Clayden J, Bladon M, Ichihara O. Dearomatising cyclisation of lithiated 1-naphthamides with a phenylglycinol-derived chiral auxiliary: asymmetric synthesis of an arylkainoid and a kainoid-like pyroglutamate. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)00502-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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