a powerful tool for the synthesis of new polymer architectures. Materials available today by this route range from simple homopolymers such as linear and branched polyethylene, to atactic or tactic poly(alpha-olefins), to end-functionalized polymers and block copolymers. This review article summarizes recent developments in this rapidly growing research area at the interface of synthetic and mechanistic
Enantioselective synthesis of epoxides by α-deprotonation—electrophile trapping of achiral epoxides
作者:David M. Hodgson、Timothy J. Buxton、Iain D. Cameron、Emmanuel Gras、Eirene H. M. Kirton
DOI:10.1039/b309717j
日期:——
Enantioselective α-deprotonation of achiral epoxides 1, 21, and 26 using organolithiums in the presence of (â)-sparteine 2 and subsequent electrophile trapping gives access to enantioenriched trisubstituted epoxides 9â17, 22, 23, 27 and 28
(in up to 86% ee).
Electrophile induced reactions of medium ring vinyl- and 1,2-epoxy-silanes and related compounds
作者:Adam P. Wells、Bruce H. Riches、William Kitching
DOI:10.1039/c39920001575
日期:——
Deuterium labelling studies confirm extensive trans-annular participation in acidolysis, acetylation and brominolysis of 1,2-epoxy-1-trimethylsilylcyclooctane and (E)-1-trimethylsilylcyclooctene, and require revision of previous mechanistic proposals.
2 with boron trifluoride etherate. With aqueous sulphuric acid the products are due to both transannular ring closure, 2, and transannular hydride migration, 3 and 4. trans-Cyclooctene derivatives 3 and 4 are formed by the trans-elimination of trimethylsilanol from the likely intermediate β-hydroxysilanes 10 and 11. The results with methanolic sulphuric acid are similar. It is also noticed that the