51
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Šnajdr I, Pavlík J, Schiller R, Kuneš J, Pour M. Pentenolide Analogues of Antifungal Butenolides: Strategies Towards 3,6-Disubstituted Pyranones and Unexpected Loss of Biological Effect. ACTA ACUST UNITED AC 2007. [DOI: 10.1135/cccc20071472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pentenolide analogues of antifungal 3,5-disubstituted butenolides were prepared by oxidative cyclization of 2-(substituted aryl)hex-5-enoic acids as the key step. Given the limitations of the methodology, another approach to the title compounds based on the Pd-catalyzed carbonylative lactonization of 4-iodo-3-en-1-ols was developed, and the carbonylation conditions were optimized. While the former sequence allows only the introduction of a substituted methyl at C6, pyranones bearing a range of various C-substituents at C6 can be prepared by the latter. Somewhat surprisingly, unlike the corresponding butenolides with the same substitution pattern, the title pentenolides possess no antifungal or cytostatic activity.
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52
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Boucard V, Broustal G, Campagne JM. Synthetic Approaches to α,β‐Unsaturated δ‐Lactones and Lactols. European J Org Chem 2006. [DOI: 10.1002/ejoc.200600570] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Valérie Boucard
- Institut de Chimie des Substances Naturelles, Avenue de la Terrasse, Bat. 27, 91198 Gif‐Sur‐Yvette, France
| | - Garance Broustal
- Institut de Chimie des Substances Naturelles, Avenue de la Terrasse, Bat. 27, 91198 Gif‐Sur‐Yvette, France
| | - Jean Marc Campagne
- Institut de Chimie des Substances Naturelles, Avenue de la Terrasse, Bat. 27, 91198 Gif‐Sur‐Yvette, France
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53
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Fürstner A, Nevado C, Tremblay M, Chevrier C, Teplý F, Aïssa C, Waser M. Total Synthesis of Iejimalide B. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200601860] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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54
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Fürstner A, Nevado C, Tremblay M, Chevrier C, Teplý F, Aïssa C, Waser M. Total Synthesis of Iejimalide B. Angew Chem Int Ed Engl 2006; 45:5837-42. [PMID: 16874828 DOI: 10.1002/anie.200601860] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Alois Fürstner
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany.
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55
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Marshall JA, Eidam P, Eidam HS. (R)- and (S)-4-TIPS-3-butyn-2-ol. Useful Precursors of Chiral Allenylzinc and Indium Reagents. J Org Chem 2006; 71:4840-4. [PMID: 16776511 DOI: 10.1021/jo060542k] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A convenient route to the enantiomers of 4-TIPS-3-butyn-2-ol of >95% enantiomeric purity by reduction of the ynone precursor 4 with the Noyori N-tosyl-1,2-diphenylethylenediamineruthenium cymene catalyst is described. The mesylate derivative of the (S) enantiomer (1c) is converted in situ to an allenylzinc or indium reagent in the presence of a catalyst derived from Pd(OAc)2 and Ph3P and either Et2Zn or InI. A second in situ addition of these reagents to aldehydes leads to anti homopropargylic alcohol adducts. The additions proceed in generally high (60-90%) yield with modest to excellent diastereoselectivity and high enantioselectivity. Only slight mismatching (<5%) is observed with chiral alpha-methyl and alpha-silyloxy aldehydes. Additions to alpha-substituted enals are highly diastereoselective, while beta,beta-disubstituted enals afford ca. 2:1 mixtures of anti and syn adducts.
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Affiliation(s)
- James A Marshall
- Department of Chemistry, University of Virginia, McCormick Road, P.O. Box 400319, Charlottesville, Virginia 22904-4319, USA.
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56
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Ma S, He Q. The cyclopropyl effect on the regioselectivity of coupling reactions involving the lithiation of 1-cyclopropyl-2-arylacetylenes. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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57
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Li QR, Gu CZ, Yin H. Tin-Indium Mediated and Microwave Assisted Propargylation of Aldehydes with Propargyl Bromide. CHINESE J CHEM 2006. [DOI: 10.1002/cjoc.200690024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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58
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Affiliation(s)
- Eun Joo Kang
- Department of Chemistry, College of Natural Sciences, Seoul National University, Korea
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59
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Lee P, Kim H, Lee K. Regioselective Addition Reactions of Propargyl Bromides to Carbonyl Compounds with Gallium Catalyzed by Indium. Adv Synth Catal 2005. [DOI: 10.1002/adsc.200505046] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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60
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Xiao WJ, Alper H. Highly Stereoselective Palladium-Catalyzed Dithiocarbonylation of Propargylic Mesylates with Thiols and Carbon Monoxide. J Org Chem 2005; 70:1802-7. [PMID: 15730305 DOI: 10.1021/jo047938l] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Highly stereoselective dithiocarbonylation of propargylic mesylates with thiols and carbon monoxide has been developed by the use of tetrakis(triphenylphosphine)palladium(0) as the catalyst at 90 degrees C in THF. The reaction affords the corresponding dithioesters in good to excellent yields. For some secondary and tertiary propargylic alcohols with a terminal or internal triple bond, the reaction stereoselectively produces E-dithioesters as products. The dithiocarbonylation is believed to proceed via allenylpalladium and allenyl ester intermediates, and the high stereoselectivity might be rationalized by a mechanism where nucleophilic attack of a Pd(0)L(n) species on the allenyl sp carbon occurs from the less hindered side of an alkyl substituent.
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Affiliation(s)
- Wen-Jing Xiao
- Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
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61
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Abstract
A concise route to the common polyketide fragment5of crocacin A-D (1-4) is presented which has previously been converted into all members of this fungicidal and cytotoxic family of dipeptidic natural products by various means. Our synthesis features asyn-selective titanium aldol reaction controlled by a valinol-derived auxiliary, a zinc-mediated, palladium-catalyzedanti-selective addition of propargyl mesylate10to the chiral aldehyde9, as well as a comparison of palladium-catalyzed Stille and Suzuki cross-coupling reactions for the formation of the diene moiety of the target.
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62
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Abstract
A concise total synthesis of the cytotoxic marine natural product amphidinolide X (1) is described. A key step of the highly convergent route to this structurally rather unusual macrodiolide derivative consists of a newly developed, highly syn selective formation of allenol 6 by an iron-catalyzed ring opening reaction of the enantioenriched propargyl epoxide 5 (derived from a Sharpless epoxidation) with a Grignard reagent. Allenol 6 was then cyclized with the aid of Ag(I) to give dihydrofuran 7 containing the (R)-configured quarternary sp3 chiral center at C19 of the target. The anti-configured chiral centers at C10 and C11 were formed by the palladium-catalyzed, Et2Zn-promoted addition of propargyl mesylate 12 to the functionalized aldehyde 11. The key fragment coupling at the C13-C14 bond was achieved by the "9-MeO-9-BBN" variant of the alkyl-Suzuki reaction. Finally, the 16-membered macrodiolide ring was formed by a Yamaguchi esterification/lactonization strategy.
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Affiliation(s)
- Olivier Lepage
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim/Ruhr, Germany
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63
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Defosseux M, Blanchard N, Meyer C, Cossy J. Total Synthesis of Zincophorin and Its Methyl Ester. J Org Chem 2004; 69:4626-47. [PMID: 15230584 DOI: 10.1021/jo0496042] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A total synthesis of the naturally occurring ionophore zincophorin has been realized. The route features an intramolecular oxymercuration of a cyclopropanemethanol and a Carroll-Claisen rearrangement for the respective elaboration of the C1-C12 and C13-C25 subunits, which have been assembled by using a highly diastereoselective titanium-mediated aldol condensation.
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Affiliation(s)
- Magali Defosseux
- Laboratoire de Chimie Organique, asocié au CNRS, ESPCI, 10 rue Vauquelin 75231 Paris Cedex 05 - France
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64
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Marshall JA, Ellis K. Applications of chiral allenylzinc additions and Noyori asymmetric reductions to an enantioselective synthesis of a C3–C13 precursor of the polyketide phosphatase inhibitor cytostatin. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2003.12.067] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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65
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Defosseux M, Blanchard N, Meyer C, Cossy J. Total Synthesis of Zincophorin Methyl Ester. Org Lett 2003; 5:4037-40. [PMID: 14572243 DOI: 10.1021/ol035177n] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text]. A convergent total synthesis of the methyl ester of zincophorin, an ionophore antibiotic, has been realized relying on a diastereoselective titanium-mediated aldol coupling between the C1-C12 and C13-C25 subunits. The latter fragment was prepared by using a Carroll-Claisen rearrangement.
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Affiliation(s)
- Magali Defosseux
- Laboratoire de Chimie Organique, associé au CNRS, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05, France
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66
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Lin MJ, Loh TP. Indium-Mediated Reaction of Trialkylsilyl Propargyl Bromide with Aldehydes: Highly Regioselective Synthesis of Allenic and Homopropargylic Alcohols. J Am Chem Soc 2003; 125:13042-3. [PMID: 14570474 DOI: 10.1021/ja037410i] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High regioselective preparation of either the allenic alcohols or homopropargylic alcohols using the indium-mediated reaction of trialkylsilyl propargyl bromides with various aldehydes has been accomplished. By just changing the silyl groups and the reaction conditions, both the allenic and homopropargylic alcohols can be obtained in high regioselectivities.
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Affiliation(s)
- Man-Jing Lin
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
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67
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68
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Lee W, Kim KH, Surman MD, Miller MJ. Stereo- and regioselectivity of Pd(0)/InI-mediated allylic additions to aldehydes and ketones. In situ generation of allylindium(III) intermediates from N-acylnitroso Diels-Alder cycloadducts and 1-amino-4-acetoxycyclopentenes. J Org Chem 2003; 68:139-49. [PMID: 12515472 DOI: 10.1021/jo026488z] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acylnitroso Diels-Alder cycloadduct (11, 37, and 45)- and cyclopentenyl acetate (8 and 9)-derived allylindium(III) species were generated in situ from palladium(0) catalysts and indium(I) iodide, and the stereo- and regiochemistry of their additions to aldehydes and ketones were investigated. Solvent, catalyst, and ionic effects were examined for the reaction of N-acetyl cycloadduct (11) and benzyloxyacetaldehyde (10). The solvent mixture of THF/H(2)O with Pd(OAc)(2).PPh(3) catalysis was found to be optimal. The addition of N-acetyl cycloadduct to aliphatic aldehydes afforded products in good yields and high regio- and stereoselectivity, with the cis-1,4-isomers constituting 90-95% of the products. The reactions with N-Boc (37a) and N-methylcarbamate (37b) cycloadducts also gave the cis-1,4-products predominantly. The same regio- and stereoselectivity applied to the reactions of 4-acetoxy-1-(N-hydroxyphenyacetamido)cyclopentene (8). 4-Acetoxy-1-phenylacetamidocyclopentene (9), however, afforded trans-1,4-products exclusively. Mechanistic speculations involving chelated transition states are described.
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Affiliation(s)
- Wenlin Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA
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69
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Marshall JA, Bourbeau MP. Second-generation synthesis of the polypropionate subunit of callystatin A based on regioselective internal alkyne hydrostannation. Org Lett 2002; 4:3931-4. [PMID: 12599495 DOI: 10.1021/ol026791m] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[formula: see text] An improved route to the polypropionate segment of callystatin A is described in which the efficient directed hydrostannation of an internal alkyne and subsequent iodinolysis provides a key vinylic iodide intermediate.
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Affiliation(s)
- James A Marshall
- Department of Chemistry, University of Virginia, P.O. Box 400319, McCormick Road, Charlottesville, Virginia 22904-4319, USA.
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70
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Marshall JA, Adams ND. Total synthesis of bafilomycin V(1): a methanolysis product of the macrolide bafilomycin C(2). J Org Chem 2002; 67:733-40. [PMID: 11856013 DOI: 10.1021/jo015864x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A synthesis of bafilomycin V(1), a methanolysis product of the macrolide natural product bafilomycin C(2), is described. The route utilizes chiral nonracemic allenylzinc reagents, prepared in situ from propargylic mesylates, to access key segments of this methyl ester. The acetylenic moieties of the derived homopropargylic alcohol adducts play an important role in further elaboration of these subunits. Final assemblage of the 25-carbon chain, containing 12 stereocenters, an alpha-methoxy Z,E 1,3-dienic ester, and an additional E,E 1,3-diene, was achieved through Stille coupling of an acetylene-derived vinyl stannane and vinyl iodide of approximate equal complexity. Attempted cyclization of several C15 hydroxy acid derivatives to the 16-membered lactone bafilomycin A(1), a potent inhibitor of vacuolar ATPases, could not be achieved.
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Affiliation(s)
- James A Marshall
- Department of Chemistry, University of Virginia, McCormick Road, P.O. Box 400319, Charlottesville, Virginia 22904, USA.
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71
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Marshall JA, Schaaf GM. Synthesis of stereopentad analogues of the C14-C22 segment of callystatin A through additions of chiral allenylzinc reagents to stereotriads. J Org Chem 2001; 66:7825-31. [PMID: 11701042 DOI: 10.1021/jo015936k] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The addition of (P)- and (M)-allenylzinc reagents, prepared in situ through Pd-catalyzed metalation of (R)- and (S)-3-butyn-2-ol mesylates, to diastereomeric stereotriad aldehydes 8, 13, 18, and 23 of syn,syn, syn,anti, anti,anti, and anti,syn stereochemistry was examined. Additions to the former two aldehydes afforded the four anti adducts with high diastereoselectivity and negligible mismatching. Significant mismatching was observed with the latter two aldehydes and the (M)-allenylzinc reagent. An evaluation of possible transition states is presented in consideration of steric and dipolar control elements.
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Affiliation(s)
- J A Marshall
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA.
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72
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Bluet G, Bazán-Tejeda B, Campagne JM. Catalytic asymmetric access to alpha,beta unsaturated delta-lactones through a vinylogous aldol reaction: application to the total synthesis of the Prelog-Djerassi lactone. Org Lett 2001; 3:3807-10. [PMID: 11700144 DOI: 10.1021/ol0168317] [Citation(s) in RCA: 52] [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 one-step catalytic asymmetric access to alpha,beta unsaturated delta-lactones is described, using a vinylogous Mukaiyama-aldol reaction between a gamma-substituted dienolate and various aldehydes in the presence of Carreira catalyst CuF.(S)-tolBinap. This methodology has been further applied to a straightforward access to the Prelog-Djerassi lactone.
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Affiliation(s)
- G Bluet
- Institut de Chimie des Substances Naturelles 91198 Gif sur Yvette, France
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73
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Marshall JA, Chobanian HR, Yanik MM. Lipase-mediated resolution of 4-TMS-3-butyn-2-ol and use of the mesylate derivatives as a precursor to a highly stereoselective chiral allenylindium reagent. Org Lett 2001; 3:3369-72. [PMID: 11594836 DOI: 10.1021/ol016605x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text]. An improved procedure for the resolution of 4-trimethylsilyl-3-butyn-2-ol has been developed. The mesylate derivatives of the resolved alcohols have been found to undergo highly enantio-, regio-, and diastereoselective additions to aldehydes, leading to homopropargylic alcohol adducts.
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Affiliation(s)
- J A Marshall
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904, USA.
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74
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Cabezas JA, Pereira AR, Amey A. A new method for the preparation of 1,3-dilithiopropyne: an efficient synthesis of homopropargyl alcohols. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)01429-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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75
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Additions of enantioenriched allenylzinc and indium reagents to lactic aldehyde ethers. J Org Chem 2000; 65:8357-60. [PMID: 11101396 DOI: 10.1021/jo005658+] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Allenylzinc and indium reagents were generated in situ through Pd(0)-catalyzed metalation of (R)- and (S)-3-butyn-2-ol methanesulfonate with Et(2)Zn and InI. These reagents add to the benzyl and TBS ethers of (S)-lactic aldehyde to afford diastereomeric stereotriads in moderate to high yield. The (S)/(S) combination afforded the anti,anti adducts with 94:6-100:0 diastereoselectivity. The (R)/(S) combination was mismatched, affording a mixture of anti,syn and syn,anti adducts in diastereomeric ratios of ca. 80:20-85:15. Addition of the racemic allenylmetal reagents to the (S)-lactic aldehyde ethers afforded the products of matched and mismatched pairings in equal amount.
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76
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Marshall JA, Adams ND. Progress toward the total synthesis of bafilomycin A(1): stereoselective synthesis of the C15-C25 subunit by additions of nonracemic allenylzinc reagents to aldehydes. Org Lett 2000; 2:2897-900. [PMID: 10964393 DOI: 10.1021/ol006344b] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] A highly stereoselective synthesis of the C15-C25 subunit (2) of bafilomycin A(1) (1) has been accomplished by a route utilizing additions of chiral nonracemic allenylzinc reagents to aldehydes.
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Affiliation(s)
- J A Marshall
- Department of Chemistry, McCormick Road, P.O. Box 400319, University of Virginia, Charlottesville, Virginia 22904, USA.
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77
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Marshall JA. Synthesis and Reactions of Allylic, Allenic, Vinylic, and Arylmetal Reagents from Halides and Esters via Transient Organopalladium Intermediates. Chem Rev 2000; 100:3163-86. [PMID: 11749316 DOI: 10.1021/cr000003u] [Citation(s) in RCA: 372] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J A Marshall
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904
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78
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Synthesis of beta-hydroxy ketones and vinylsilanes from homopropargylic alcohols by intramolecular hydrosilation. Org Lett 2000; 2:2173-5. [PMID: 10891259 DOI: 10.1021/ol0061182] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Catalytic intramolecular hydrosilation of nonracemic homopropargylic alcohols affords the corresponding five-membered cyclic siloxanes regiospecifically. Oxidation or alkylmetal addition converts these intermediates into beta-hydroxy ketones or vinylsilanes under mild conditions.
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79
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Marshall JA, Yanik MM. Stereoselective synthesis of substituted ketopyranose subunits of polyketide natural products by intramolecular alkoxycarbonylation of δ-alkynyl alcohols. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(00)00705-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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80
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Marshall JA, Grant CM. Preparation of Chiral Allenylmetal Reagents from Enantioenriched Allenyl Iodides and Propargylic Mesylates. A Comparison of Indium, Bismuth, and Tin Derivatives. J Org Chem 1999; 64:8214-8219. [PMID: 11674739 DOI: 10.1021/jo990938e] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chiral allenylmetal halides were prepared starting from enantioenriched ( approximately 95% ee) 1-octyn-3-ol mesylate (1) and 3-butyn-2-ol mesylate (7). Addition of these transient metallo species to aldehydes in situ afforded mainly anti homopropargylic alcohol adducts of varying ee. Three approaches were explored. In the first, the mesylates were converted to allenylstannanes with Bu(3)SnLi.CuBr and the allenylmetal halide was prepared from the resulting enantioenriched allenylstannane by transmetalation with InBr(3), BiBr(3), and SnCl(4) in the presence of cyclohexanecarboxaldehyde. The configurational stability of the transient allenylmetal halide was estimated from the ee of the derived adduct. The second approach involved metalation of the allenyl iodides prepared from mesylates 7 and 1 through S(N)2' displacement with LiCuI(2). From these experiments, it was determined that allenylindium bromides and allenyltin bromides are configurationally stable under the reaction conditions. The adduct obtained from the allenylbismuth bromide was nearly racemic. A superior procedure was developed in which the propargylic mesylates 7 and 1 were converted to allenylindium iodide intermediates through treatment with InI and 5 mol % of a Pd(0) dppf catalyst in THF-HMPA, THF-DMSO, or THF-DMPU. Under these conditions, alpha-branched aldehydes were converted to anti adducts ( approximately 95:5 anti/syn) of >90% ee. Additions to unbranched aldehydes were less diastereoselective, but afforded adducts of high ee. Additions of enantiomeric allenylindium iodide reagents to (R)-beta-ODPS-alpha-methylpropanal (13) afforded diastereomeric adducts (anti,anti and anti,syn) 14, 15 and 18, 19 with excellent diastereoselectivity indicative of a high degree of reagent control. A convenient procedure for the preparation of InI from In and I(2) is also described.
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Affiliation(s)
- James A. Marshall
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
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