苯-顺-和反-1,2-二氢二醇以显着不同的速率经历酸催化脱水:k cis / k trans = 4500。这可以通过形成不同初始构象的β-羟基碳正离子中间体来解释,其中之一是通过芳香族无键共振结构(HOC 6 H 6 + ↔ HOC 6 H 5 H +)放大的超共轭稳定。MP2 计算和苯并退火对苯离子稳定性的不利影响,由 p K R暗示对苯、1-萘和 9-菲离子分别测量的 -2.3、-8.0 和 -11.9 支持了这一解释。
A highly enantioselective method for the copper-catalyzed desymmetrization of oxabenzonorbornadienes with aluminum reagents and SimplePhos as chiral ligand has been developed. The same reaction with Grignard reagents is also reported. A wide range of alkyl chains have been used with moderate to high enantioselectivity and high trans selectivity. The transfer of a methyl group is also reported with
METHOD AND CATALYST SYSTEM FOR PREPARING POLYMERS AND BLOCK COPOLYMERS
申请人:IMPERIAL INNOVATIONS LIMITED
公开号:US20160108181A1
公开(公告)日:2016-04-21
The present invention provides methods for producing block copolymers, either by the sequential addition of monomers, or using a “one-pot” method. The invention also relates to novel methods for producing polyesters by ring opening lactides and/or lactones and by copolymerising anhydrides and epoxides.