A Straightforward Synthetic Entry to Cleavamine-Type Indole Alkaloids by a Ring-Closing Metathesis−Vinyl Halide Heck Cyclization Strategy
摘要:
An indole-templated ring-closing metathesis has been used to create the central nine-membered ring of the cleavamine-type alkaloids. A subsequent intramolecular vinyl halide Heck reaction upon the resulting azacyclononene ring completes the assembly of the strained 1-azabicyclo[6.3.1]dodecane framework of the alkaloids. The usefulness of the approach is illustrated with the synthesis of (+/-)-cleavamine and (+/-)-dihydrocleavamine.
Synthesis of cleavamine-type indole alkaloids and their 5-nor derivatives by a ring-closing metathesis–vinyl halide Heck cyclization strategy
摘要:
An indole-templated RCM has been used to assemble the central medium-sized rings of the indole upper-half of vinorelbine and the cleavamine-type alkaloids. From these key intermediates, the bridged tetracyclic framework of the alkaloids is completed with the insertion of a 2-ethylpropeno unit, by N-alkylation followed by a challenging endocyclic vinyl halide Heck cyclization. The usefulness of the approach is illustrated with the synthesis of (+/-)-cleavamine and (+/-)-dihydrocleavamine. (C) 2013 Elsevier Ltd. All rights reserved.