tert-butyldimethylsilyldihalomethyllithium as a dihalomethylene dianion synthon. 1,3-rearrangement and 1,4-rearrangement of silyl group from carbon to oxide

One-pot synthesis of R(1) CH(OSiMe(2)-t-Bu)CX(2)CH(OH)R(2) (X=Cl, Br) by successive addition of two different aldehydes (R(1)CHO and R(2)CHO) has been achieved starting from tert-butyldimethylsilyldihalomethylithium. Treatment of a THF solution of the title carbanion (X=Cl) with p-MeOC(6)H(4)CHO or n-BuCHO followed by an addition of HMPA and benzaldehyde gave the corresponding 1,3-diol monosilyl ether in 83% or 45% yield, respectively. The use of oxirane in place of aldehyde as the first electrophile followed by addition of benzaldehyde provided 1,4-diol monosilyl ether.