A practical synthesis of novel alpha-dibromoalkyl- and trimethylsilylmethyl-aminoboranes and derivatives

Addition of LDA to a mixture of trimethylborate and dibromomethane in THF at a temperature of -78 degrees C leads to the formation of dibromomethyllithium and its capture by borate ester. CIB(OMe)(2) converts the resulting borate salt to dimethoxy(dibromomethyl)borane 2. N,N-Dimethylamino(methoxy) (dibromomethyl)borane 3 and N,N-bis(dimethylamino)(dibromomethyl)borane 4 were prepared by an amination reaction between N,N-dimethylaminotrimethylsilane and dimethoxy(dibromomethyl)borane 2. To obtain dichlorotrimethylsilylmethylborane 7 not containing the alpha-halomethyl group. N,N-bis(dimethylamino)(trimethylsilylmethyl)borane 5 was first obtained from the reaction of CIB(NMe2)(2) with an organolithium reagent. Dimethoxy(trimethylsilylmethyl)borane 6 was then prepared by methoxylation of compound 5. Finally, compound 7 was prepared by chlorination of 6 using BCl3. The chemical structures of these compounds were determined using C-13, H-1, B-11 NMR and GC/MS/MS techniques. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.