AN EXPLORATORY-STUDY OF SILYLATED AMINO BORONIC ESTER CHEMISTRY

Diisopropyl [bis(trimethylsilylamino)methyl]-boronate, the analogous p inacol boronic ester (3), and pinacol -tetramethyl-2,5,1-disilazol-1-y l)-methyl]boronate (8) were prepared from the corresponding (bromometh yl)boronic ester 1 or 2 and silylated lithium amide. Reaction of 3 or 8 with (dichloromethyl)lithium yielded the corresponding [1-chloro- 2- (silylated amino)ethyl]boronate 4 or 9. Further transformations of 4 t o methylthio derivative 5 and dimethylamino derivative 7 as well as co nversion of 5 to ureido derivatives 6 are described. (S,S)-1,2-dicyclo hexylethanediol [1-chloro-2-(trityloxy)-ethyl]boronate (13) has been c onverted to bis(tri-methylsilyl)amino derivative 14 and formamido deri vative 15 as well as to N-benzyl analogs 18 and 19. Attempted chain ex tensions of 14, silylated 15, or 19 with (dichloromethyl)lithium indic ated that the alkyl migration from boron to carbon is sloth, and incom plete. (C) 1997 John Wiley & Sons, Inc.