Switchable Synthetic Strategy toward Trisubstituted and Tetrasubstituted Exocyclic Alkenes
摘要:
An efficient and facile method for the construction of tri- or tetrasubstituted exocyclic alkenes is achieved via a Cu(I)-catalytic system. This protocol exhibits mild conditions, low-cost catalyst, good functional group tolerance, and good yields. The selectivity toward tri- or tetrasubstituted alkenes can be delicately controlled by adjustment of base and solvent. A preliminary mechanism study manifested that the reaction undergoes a radical process, where B(2)pin(2) plays an indispensable role.
Reactions of some alkynyl halides with Samarium(II) iodide
作者:Zhihong Zhou、Denis Larouche、Sharon M. Bennett
DOI:10.1016/0040-4020(95)00703-b
日期:1995.10
Certain alkynyl halides (6-halo-1-ynes) react with samarium(II) iodide (SmI2) to give cyclized products (methylenecyclopentanes) in good yield. We have found some interesting evidence for the presence of radical and unstable organosamarium intermediates in these reductive cyclizations. Methyl 7-halohept-2-ynoates are not. however, good substrates for this cyclization methodology.