ON THE ORDER OF ADDITION OF SODIUM DISPERSION IN REDUCTIVE DIBORATIONS OF STILBENE AND 1,2-DIPHENYLCYCLOPROPANE

摘要

Two extreme methods to add sodium dispersion were investigated in the 1,2-diboration of stilbene and the ring-opening 1,3-diboration of 1,2-diphenylcyclopropane on a 20-mmol scale.Method 1 denotes that a substrate is added to a mixture of sodium dispersion and a boron electrophile.Method 2 denotes that sodium dispersion is slowly added to a mixture of a substrate and a boron electrophile.In these four cases,no significant differences were observed in the yields of the products and their synlanti ratios,except for the diboration of stilbene by Method 1,wherein aggregation of sodium dispersion in the flask and 5 recovery of stilbene were observed.This information would be helpful in performing sodium-dispersion-mediated transformations on a large scale.