Silphos [PCl3−n(SiO2)n]: a heterogeneous phosphine reagent for the conversion of epoxides to β-bromoformates or alkenes
摘要:
Silphos [PCl3-n(SiO2)(n)] as a heterogeneous phosphine reagent is efficiently applied for the transformation of epoxides to beta-bromoformates in the presence of bromine or N-bromosuccinimide in dimethyl forinarnide at 0 degrees C. The combination of Silphos and iodine was also found Suitable for the room temperature preparation of alkenes. The use of Silphos provides the advantage of easy separation of the phosphine oxide by-product from the reaction mixture. (c) 2006 Published by Elsevier Ltd.
Reactions of epoxides and episulfides with electrophilic halogens
作者:Nasser Iranpoor、Habib Firouzabadi、Maryam Chitsazi、Abbas Ali Jafari
DOI:10.1016/s0040-4020(02)00699-3
日期:2002.8
conversion of epoxides into β-bromoformates using Ph3PBr2, Ph3P/N-bromosuccinimdes (NBS) and or Ph3P/2,4,4,6-tetrabromo-2,5-cyclohexadiene-1-one (TABCO) in DMF. Epoxides in the presence of Ph3P/I2 were converted into olefins immediately in excellent yields. The application of NBS, NCS, and TABCO as compounds carrying electrophilic halogens for the highly selective alcoholysis of epoxides and dimerization
描述了一种使用Ph 3 PBr 2,Ph 3 P / N-溴代琥珀酰亚胺(NBS)和Ph 3 P / 2,4,4,4,6-四溴-2,5-将环氧化物转化为β-溴甲酸酯的新方法。 DMF中的环己二烯-1-酮(TABCO)。在存在Ph 3 P / I 2的情况下,环氧化物立即以优异的收率转化为烯烃。还描述了NBS,NCS和TABCO作为携带亲电卤素的化合物在环氧化物的高选择性醇解和环硫化物的二聚化或醇解二聚化中的应用。