Free radical cyclizations in alkaloid total synthesis: (±)-21- oxogelsemine and (±)-gelsemine

Shogo Atarashi; Joong Kwon Choi; Deok Chan Ha; David J. Hart; Daniel Kuzmich; Chih Shone Lee; Subban Ramesh; Shung C. Wu

doi:10.1021/ja970089h

Free radical cyclizations in alkaloid total synthesis: (±)-21- oxogelsemine and (±)-gelsemine

Shogo Atarashi, Joong Kwon Choi, Deok Chan Ha, David J. Hart, Daniel Kuzmich, Chih Shone Lee, Subban Ramesh, Shung C. Wu

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89 Citations (Scopus)

Abstract

Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization-cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol-aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).

Original language	English
Pages (from-to)	6226-6241
Number of pages	16
Journal	Journal of the American Chemical Society
Volume	119
Issue number	27
DOIs	https://doi.org/10.1021/ja970089h
Publication status	Published - 1997
Externally published	Yes

ASJC Scopus subject areas

Catalysis
Chemistry(all)
Biochemistry
Colloid and Surface Chemistry

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title = "Free radical cyclizations in alkaloid total synthesis: (±)-21- oxogelsemine and (±)-gelsemine",

abstract = "Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization-cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol-aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).",

author = "Shogo Atarashi and Choi, {Joong Kwon} and Ha, {Deok Chan} and Hart, {David J.} and Daniel Kuzmich and Lee, {Chih Shone} and Subban Ramesh and Wu, {Shung C.}",

year = "1997",

doi = "10.1021/ja970089h",

language = "English",

volume = "119",

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journal = "Journal of the American Chemical Society",

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TY - JOUR

T1 - Free radical cyclizations in alkaloid total synthesis

T2 - (±)-21- oxogelsemine and (±)-gelsemine

AU - Atarashi, Shogo

AU - Choi, Joong Kwon

AU - Ha, Deok Chan

AU - Hart, David J.

AU - Kuzmich, Daniel

AU - Lee, Chih Shone

AU - Ramesh, Subban

AU - Wu, Shung C.

PY - 1997

Y1 - 1997

N2 - Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization-cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol-aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).

AB - Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization-cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol-aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).

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Free radical cyclizations in alkaloid total synthesis: (±)-21- oxogelsemine and (±)-gelsemine

Abstract

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