Ring-Expansion of MCPs in the Presence of DIAD or DEAD and Lewis Acids
作者:Li-Xiong Shao、Min Shi
DOI:10.1002/ejoc.200300515
日期:2004.1
Treatment of methylenecyclopropanes (MCPs) with DIAD or DEAD in MeCN under mild conditions in the presence of Lewisacid Zr(OTf)(4) gave the cyclobutanone ring-expansion products in good to high yields based on the employed DIAD or DEAD. From a deuterium labeling experiment, the oxygen atom is derived from ambient water. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
Dihalogenation ofgem-Aryl-Disubstituted Methylenecyclopropanes by DEAD, DIAD/TiX4 or Free Halogen
作者:Li-Xiong Shao、Lin-Jing Zhao、Min Shi
DOI:10.1002/ejoc.200400388
日期:2004.12
gem-aryl-disubstituted methylenecyclopropanes with TiX4/diethyl azodicarboxylate and TiX4/diisopropyl azodicarboxylate in 1,2-dichloroethane gave the dihalogenated ring-opened product, 2,4-dihalobut-1-ene, in moderate-to-excellent yields under mild conditions. On the basis of the proposed Orton-type mechanism, we found that this reaction can also be carried out with freehalogens such as bromine or iodine