An Anionic C3−C5 Ring Expansion of β-Ketocyclopropanes to Cyclopentenols
摘要:
[GRAPHICS]When treated with base, beta-ketocyclopropylcarboxylates ring-open to initially afford either cis or trans alpha,beta-unsaturated ketones. The cis isomer undergoes an intramolecular aldol reaction to afford allylic cyclopentenols in high yield and excellent diastereoselectivity. Choice of base is key to a successful outcome.
Exploitation of ylide steric bulk to alter cyclopropanation outcome during the reaction of 1,2-dioxines and stabilised phosphorus ylides
作者:Thomas D. Avery、Ben W. Greatrex、Dennis K. Taylor、Edward R. T. Tiekink
DOI:10.1039/b001975p
日期:——
A new approach for the synthesis of diastereomerically pure cyclopropanes from 1,2-dioxines and sterically bulky stabilised phosphorus ylides is presented.