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Cycloaddition chemistry of 2-vinyl-substituted indoles and related heteroaromatic systems.
J Org Chem. 2005 Mar 18; 70(6):2206-18.JO

Abstract

[reaction: see text] The intramolecular Diels-Alder cycloaddition reaction (IMDAF) of several N-phenylsulfonylindolyl-substituted furanyl carbamates containing a tethered pi-bond on the indole ring were examined as an approach to the iboga alkaloid catharanthine. Only in the case where the tethered pi-bond contained two carbomethoxy groups did the [4 + 2]-cycloaddition occur. Push-pull dipoles generated from the Rh(II)-catalyzed reaction of diazo imides, on the other hand, undergo successful intramolecular 1,3-dipolar cycloaddition across both alkenyl and heteroaromatic pi-bonds to provide novel pentacyclic compounds in good yield and in a stereocontrolled fashion. The facility of the cycloaddition was found to be critically dependent on conformational factors in the transition state. Ligand substitution in the rhodium(II) catalyst markedly altered the product ratio between [3 + 2]-cycloaddition and intramolecular C-H insertion. The variation in reactivity reflects the difference in electrophilicity between the various rhodium carbenoid intermediates. Intramolecular C-H insertion is enhanced with the more electrophilic carbene generated using Rh(II) perfluorobutyrate.

Authors+Show Affiliations

Padwa A
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA. chemap@emory.edu
Lynch SM
No affiliation info available
Mejía-Oneto JM
No affiliation info available
Zhang H
No affiliation info available

MeSH

CatalysisCyclizationHeterocyclic CompoundsImidesIndolesMolecular ConformationRhodiumStereoisomerism

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15760207

Citation

Padwa, Albert, et al. "Cycloaddition Chemistry of 2-vinyl-substituted Indoles and Related Heteroaromatic Systems." The Journal of Organic Chemistry, vol. 70, no. 6, 2005, pp. 2206-18.
Padwa A, Lynch SM, Mejía-Oneto JM, et al. Cycloaddition chemistry of 2-vinyl-substituted indoles and related heteroaromatic systems. J Org Chem. 2005;70(6):2206-18.
Padwa, A., Lynch, S. M., Mejía-Oneto, J. M., & Zhang, H. (2005). Cycloaddition chemistry of 2-vinyl-substituted indoles and related heteroaromatic systems. The Journal of Organic Chemistry, 70(6), 2206-18.
Padwa A, et al. Cycloaddition Chemistry of 2-vinyl-substituted Indoles and Related Heteroaromatic Systems. J Org Chem. 2005 Mar 18;70(6):2206-18. PubMed PMID: 15760207.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cycloaddition chemistry of 2-vinyl-substituted indoles and related heteroaromatic systems. AU - Padwa,Albert, AU - Lynch,Stephen M, AU - Mejía-Oneto,José M, AU - Zhang,Hongjun, PY - 2005/3/12/pubmed PY - 2005/6/9/medline PY - 2005/3/12/entrez SP - 2206 EP - 18 JF - The Journal of organic chemistry JO - J Org Chem VL - 70 IS - 6 N2 - [reaction: see text] The intramolecular Diels-Alder cycloaddition reaction (IMDAF) of several N-phenylsulfonylindolyl-substituted furanyl carbamates containing a tethered pi-bond on the indole ring were examined as an approach to the iboga alkaloid catharanthine. Only in the case where the tethered pi-bond contained two carbomethoxy groups did the [4 + 2]-cycloaddition occur. Push-pull dipoles generated from the Rh(II)-catalyzed reaction of diazo imides, on the other hand, undergo successful intramolecular 1,3-dipolar cycloaddition across both alkenyl and heteroaromatic pi-bonds to provide novel pentacyclic compounds in good yield and in a stereocontrolled fashion. The facility of the cycloaddition was found to be critically dependent on conformational factors in the transition state. Ligand substitution in the rhodium(II) catalyst markedly altered the product ratio between [3 + 2]-cycloaddition and intramolecular C-H insertion. The variation in reactivity reflects the difference in electrophilicity between the various rhodium carbenoid intermediates. Intramolecular C-H insertion is enhanced with the more electrophilic carbene generated using Rh(II) perfluorobutyrate. SN - 0022-3263 UR - https://www.unboundmedicine.com/medline/citation/15760207/Cycloaddition_chemistry_of_2_vinyl_substituted_indoles_and_related_heteroaromatic_systems_ DB - PRIME DP - Unbound Medicine ER -