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Jansana S, Coussanes G, Puig J, Diaba F, Bonjoch J. Synthesis of Azabicyclic Building Blocks for
Daphniphyllum
Alkaloid Intermediates Featuring
N
‐Trichloroacetyl Enamide 5‐
endo
‐
trig
Radical Cyclizations. Helv Chim Acta 2019. [DOI: 10.1002/hlca.201900188] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Sergi Jansana
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUBUniversitat de Barcelona Av. Joan XXIII s/n 08028 Barcelona Spain
| | - Guilhem Coussanes
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUBUniversitat de Barcelona Av. Joan XXIII s/n 08028 Barcelona Spain
- Syngenta Crop Protection AG Route de l'Ile au Bois–site chimique CH-1870 Monthey
| | - Jordi Puig
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUBUniversitat de Barcelona Av. Joan XXIII s/n 08028 Barcelona Spain
| | - Faiza Diaba
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUBUniversitat de Barcelona Av. Joan XXIII s/n 08028 Barcelona Spain
| | - Josep Bonjoch
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUBUniversitat de Barcelona Av. Joan XXIII s/n 08028 Barcelona Spain
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2
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Baker SR, Goodall K, Parsons AF, Wilson M. Tributyltin Hydride-Mediated Tandem reactions of Dehydroalanines Leading to α-Substituted Pyroglutamates. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/030823400103167651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tributyltin hydride-mediated cyclisation of dehydroalanines produces an intermediate captodative radical, which can be trapped by reaction with oxygen- or carbon-centred radicals or (principally) electron-poor alkenes, to provide a quick approach to a variety of α-substituted pyroglutamates.
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Affiliation(s)
- S. Richard Baker
- Eli Lilly and Company Ltd, Lilly Research Centre, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Karen Goodall
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Andrew F. Parsons
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - Michelle Wilson
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
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3
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Copper mediated cyclization of 1-substituted enamides, dienamides and trienamides: regiochemistry, indigoid formation and methyl migration-aromatization. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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4
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Clark AJ, Curran DP, Fox DJ, Ghelfi F, Guy CS, Hay B, James N, Phillips JM, Roncaglia F, Sellars PB, Wilson P, Zhang H. Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and Implications for their Cyclization Reactions. J Org Chem 2016; 81:5547-65. [PMID: 27267662 DOI: 10.1021/acs.joc.6b00889] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG(⧧) rotation varied between <8.0 and 31.0 kcal mol(-1)). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG(⧧) rotation >20 kcal mol(-1)) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol(-1)) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical-polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.
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Affiliation(s)
- Andrew J Clark
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh , Pittsburgh Pennsylvania 15260, United States
| | - David J Fox
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Franco Ghelfi
- Dipartmento di Scienze Chimiche e Geologiche, Univerita degli Studi di Modena e Reggio Emilia , Via Campi 103, 41125 Modena, Italy
| | - Collette S Guy
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Benjamin Hay
- Department of Chemistry, University of Pittsburgh , Pittsburgh Pennsylvania 15260, United States
| | - Natalie James
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Jessica M Phillips
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Fabrizio Roncaglia
- Dipartmento di Scienze Chimiche e Geologiche, Univerita degli Studi di Modena e Reggio Emilia , Via Campi 103, 41125 Modena, Italy
| | - Philip B Sellars
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Paul Wilson
- Department of Chemistry, University of Warwick , Coventry, West Midlands CV4 7AL, U.K
| | - Hanmo Zhang
- Department of Chemistry, University of Pittsburgh , Pittsburgh Pennsylvania 15260, United States
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5
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Unusual rearrangement and dearomatization reactions in Cu(I)-catalyzed atom transfer radical cyclizations from N-(1-phenylethyl)trichloroacetamides. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.04.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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El Bialy SAA. Efficient synthesis of (−)-γ-lycorane alkaloid by two Bu3SnH-mediated radical cyclisations. Nat Prod Res 2008; 22:1176-88. [DOI: 10.1080/14786410701838205] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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7
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8
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Majumdar KC, Basu PK, Mukhopadhyay PP. Formation of five- and six-membered heterocyclic rings under radical cyclisation conditions. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.05.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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10
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Chatgilialoglu C, Ferreri C, Guerra M, Timokhin V, Froudakis G, Gimisis T. 5-Endo-trig radical cyclizations: disfavored or favored processes? J Am Chem Soc 2002; 124:10765-72. [PMID: 12207532 DOI: 10.1021/ja0261731] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Relative kinetic data were determined for the 5-endo-trig cyclization of radical 12 compared to hydrogen abstraction from (TMS)(3)SiH in the temperature range of 344-430 K, which allows for the estimation of a rate constant of 2 x 10(4) s(-)(1) at 298 K with an activation energy of ca. 9 kcal/mol for the cyclization process. The 5-endo-trig cyclization of a variety of radicals that afford five-membered nitrogen-containing heterocycles was addressed computationally at the UB3LYP/6-31G level. The 5-endo vs 4-exo mode of cyclication and the effect of delocalization of the unpaired electron in the transition state were investigated. Because the ring formed during cyclization contains five sp(2) centers, electrocyclization via a pentadienyl-like resonance form was also considered. For comparison, similar calculations were performed for 4-penten-1-yl and related radicals. The factors that affect the activation energies of homolytic 5-endo-trig cyclization were determined. In the absence of steric or conformational effects, the endo cyclization to form the five-membered ring was strongly favored over exo cyclization to form the four-membered ring not only on thermodynamic grounds but also kinetically. When a substituent on the double bond was able to delocalize the unpaired electron in the transition state of the 4-exo path, the two modes of cyclization became kinetically comparable. These results have an important bearing on the generalization of the Baldwin-Beckwith rules, which classified the 5-endo-trig radical cyclization as a "disfavored" process.
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11
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Miranda LD, Zard SZ. A short synthesis of the erythrina skeleton and of (+/-)-alpha-lycorane. Org Lett 2002; 4:1135-8. [PMID: 11922801 DOI: 10.1021/ol025534e] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] A new nonchain 5-endo radical cyclization starting with xanthates was exploited in a short synthesis of (+/-)-alpha-lycorane and the erythrina ring system.
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Affiliation(s)
- Luis D Miranda
- Laboratoire de Sythèse Organique associé au CNRS, Ecole Polytechnique, 91128 Palaiseau, France
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12
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Sibi MP, Sausker JB. The role of the achiral template in enantioselective transformations. Radical conjugate additions to alpha-methacrylates followed by hydrogen atom transfer. J Am Chem Soc 2002; 124:984-91. [PMID: 11829606 DOI: 10.1021/ja016839b] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have evaluated various achiral templates (1a-g, 10, and 16) in conjunction with chiral Lewis acids in the conjugate addition of nucleophilic radicals to alpha-methacrylates followed by enantioselective H-atom transfer. Of these, a novel naphthosultam template (10) gave high enantioselectivity in the H-atom-transfer reactions with ee's up to 90%. A chiral Lewis acid derived from MgBr(2) and bisoxazoline (2) gave the highest selectivity in the enantioselective hydrogen-atom-transfer reactions. Non-C(2) symmetric oxazolines (20-25) have also been examined as ligands, and of these, compound 25 gave optimal results (87% yield and 80% ee). Insights into rotamer control in alpha-substituted acrylates and the critical role of the tetrahedral sulfone moiety in realizing high selectivity are discussed.
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Affiliation(s)
- Mukund P Sibi
- Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105-5516, USA
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13
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C. Majumdar K, Kumar Basu P. Formation of Five- and Six-membered Heterocyclic Rings by Radical Cyclization. HETEROCYCLES 2002. [DOI: 10.3987/rev-02-557] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Sibi MP, Asano Y, Sausker JB. Enantioselective Hydrogen Atom Transfer Reactions: Synthesis ofN-Acyl-α-Amino Acid Esters. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20010401)113:7<1333::aid-ange1333>3.0.co;2-g] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Sibi MP, Asano Y, Sausker JB. Enantioselective Hydrogen Atom Transfer Reactions: Synthesis of N-Acyl-alpha-Amino Acid Esters This work was supported by the National Institutes of Health (NIH-GM-54656). Angew Chem Int Ed Engl 2001; 40:1293-1296. [PMID: 11301456 DOI: 10.1002/1521-3773(20010401)40:7<1293::aid-anie1293>3.0.co;2-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mukund P. Sibi
- Department of Chemistry North Dakota State University Fargo, ND 58105-5516 (USA)
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16
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Ikeda M, A. A. El Bialy S, Ohtani S, Sato T. 5-endo-trig Radical Cyclization of N-Benzyl-2-halo-N-(6-oxo-1-cyclohexen-1-yl)acetamides. HETEROCYCLES 2001. [DOI: 10.3987/com-00-s(i)83] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Preparation of N-Heterocycles by Radical Cyclisation of Enamides Mediated by Manganese(III) or Copper(I). A Comparison of Cyclisation Methods. Tetrahedron 2000. [DOI: 10.1016/s0040-4020(00)00316-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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18
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Knowles HS, Parsons AF, Pettifer RM, Rickling S. Desulfonylation of Amides using Tributyltin Hydride, Samarium Diiodide or Zinc/Titanium Tetrachloride. A Comparison of Methods. Tetrahedron 2000. [DOI: 10.1016/s0040-4020(00)00025-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Copper(I) reactions in N-heterocycle synthesis: efficient preparation of substituted pyrrolidinones. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01805-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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20
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Clark AJ, Dell CP, Ellard JM, Hunt NA, McDonagh JP. Efficient room temperature copper(I) mediated 5-endo radical cyclisations. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01806-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Aurrecoechea J, Fernández A, Gorgojo J, Saornil C. Synthesis of 2,3-disubstituted pyrrolidines by intramolecular addition of α-aminoalkyl radicals to electron deficient C C bonds. Tetrahedron 1999. [DOI: 10.1016/s0040-4020(99)00359-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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22
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Cassayre J, Quiclet-Sire B, Saunier JB, Zard SZ. Nickel powder promoted 5-endo radical cyclisations. A concise approach to Erythrina alkaloids. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)02036-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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23
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24
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Richard Baker S, Parsons AF, Pons JF, Wilson M. Tandem radical cyclisations leading to indolizidinones and pyrrolizidinones. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)01542-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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25
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Davies DT, Kapur N, Parsons AF. Manganese(III) reactions in N-heterocycle synthesis: The preparation of substituted pyrrolidinones. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)00746-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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26
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Richard Baker S, Parsons AF, Wilson M. Radical reactions leading to substituted pyroglutamates. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)00254-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Quirante J, Escolano C, Merino A, Bonjoch J. First Total Synthesis of (±)-Melinonine-E and (±)-Strychnoxanthine Using a Radical Cyclization Process as the Core Ring-Forming Step. J Org Chem 1998. [DOI: 10.1021/jo971148c] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Josefina Quirante
- Laboratory of Organic Chemistry, Faculty of Farmacy, University of Barcelona, 08028-Barcelona, Spain
| | - Carmen Escolano
- Laboratory of Organic Chemistry, Faculty of Farmacy, University of Barcelona, 08028-Barcelona, Spain
| | - Alma Merino
- Laboratory of Organic Chemistry, Faculty of Farmacy, University of Barcelona, 08028-Barcelona, Spain
| | - Josep Bonjoch
- Laboratory of Organic Chemistry, Faculty of Farmacy, University of Barcelona, 08028-Barcelona, Spain
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28
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Davies DT, Goodall K, Kapur N, O'Brien M, Parsons AF. The Synthesis of Dehydroamino Acids from Pyruvic Acid. SYNTHETIC COMMUN 1997. [DOI: 10.1080/00397919708007306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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29
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Benedetti M, Forti L, Ghelfi F, Pagnoni UM, Ronzoni R. Halogen atom transfer radical cyclization of N-allyl-N-benzyl-2,2-dihaloamides to 2-pyrrolidinones, promoted by Fe0-FeCl3 or CuCl-TMEDA. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(97)00908-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Quirante J, Escolano C, Costejà L, Bonjoch J. Cyclization of 1-(carbamoyl)dichloromethyl radicals upon activated alkenes. A new entry to 2-azabicyclo[3.3.1]nonanes. Tetrahedron Lett 1997. [DOI: 10.1016/s0040-4039(97)01590-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Tejero T, Dondoni A, Rojo I, Merchán FL, Merino P. 1,3-Dipolar cycloaddition of C-(2-thiazolyl)nitrones to chiral acrylates. Synthesis of enantiopure α-amino-2-alkylthiazoles and 5-formylpyrrolidin-2-ones. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(97)00040-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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32
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Easton CJ. Free-Radical Reactions in the Synthesis of alpha-Amino Acids and Derivatives. Chem Rev 1997; 97:53-82. [PMID: 11848865 DOI: 10.1021/cr9402844] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christopher J. Easton
- Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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Quirante J, Escolano C, Massot M, Bonjoch J. Synthesis of 2-azabicyclo[3.3.1]nonanes by means of (carbamoyl)dichloromethyl radical cyclization. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(96)01051-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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