The steric course of the conversion of some bromohydrins into dibromides with phosphorus tribromide and thionyl bromide
作者:G. Bellucci、F. Marioni、A. Marsili
DOI:10.1016/s0040-4020(01)82952-5
日期:1969.1
with SOBr2, SOBr2-pyridine. and PBr3 was investigated. While the reactions with SOBr2 produced dibromides with low specific rotations (positive in the absence and negative in the presence of pyridine), PBr3 gave a levorotatory product with much higher optical activity. Equilibrated mixtures of trans-dibromides were obtained in the reactions of the 4-t-butylcyclohexene trans-diaxial bromohydrins with SOBr2
(S)-(-)-2-溴-1-丁醇用SOBr 2,SOBr 2-吡啶转化为1,2-二溴丁烷。研究了PBr 3。尽管与SOBr 2的反应产生的二溴化物具有低的比旋光(在不存在吡啶时为正,在吡啶存在下为负),但PBr 3产生的左旋产物具有更高的旋光性。在4-叔丁基环己烯反式双轴溴代醇与SOBr 2和SOBr 2-吡啶,而与PBr 3的反应中获得反式-二溴化物的平衡混合物二溴化物的双轴率超过90%。从数据可以推断出(-)-1,2-二溴丁烷几乎可以肯定地具有(S)构型。在二氢辛可宁存在下1-丁烯的不对称溴化得到右旋的1,2-二溴丁烷。