A ring closing metathesis approach to the indole alkaloid mitralactonine
摘要:
An efficient utilisation of RCM leading to a convenient synthesis of a pentacyclic indole alkaloid is described. (c) 2006 Elsevier Ltd. All rights reserved.
C-4 or C-12 ethyl substituted 1,5-methanoazocino[4,3-b]indoles, which constitute the tetracyclic framework of uleine alkaloids as well as the ABDE substructure of the Strychnos alkaloid family, have been synthesized by novel 6-exo and 6-endo cyclizations of selenoester-derived 2-indolylacyl radicals upon 5-ethyl-1,2,3,6- and 3-ethyl-1,2,5,6-tetrahydropyridines, respectively.
Rhodium(I)-catalyzed enantioselective cyclization of enynes through C(sp3)–H bond activation was investigated. It was found that the cyclization of enynes having a tert-butyl moiety on the alkene afforded a spirocyclic compound (up to 92% ee), while the cyclization of enynes having an isopropyl or an ethyl group on the alkene gave a cyclic diene (up to 98% ee). Furthermore, an intermolecular competition
1,3-Elimination reactions of (3,4-epoxybutyl)stannanes. Approach to the synthesis of hirsutene
作者:Louis Plamondon、James D. Wuest
DOI:10.1021/jo00006a020
日期:1991.3
An advanced tricyclic precursor of hirsutene (3) was prepared by a 1,3-elimination reaction of spirocyclic epoxy stannane 7b. Compound 7b was synthesized efficiently from hydroxycyclohexenone 8b by conjugate addition of [(CH3)3Sn]2CuLi, Wittig methylenation, and VO(acac)2-catalyzed epoxidation. Intermediate 8b was prepared in five steps from the known enone 9 in 18% overall yield. An improved synthesis makes compound 9 available in four efficient steps from keto ester 12.
PLAMONDON, LOUIS;WUEST, JAMES D., J. ORG. CHEM., 56,(1991) N, C. 2076-2081