Ng. Bhat et Cp. Aguirre, Simple procedures for the preparation of (Z)-2-(1-trimethylsilyl-1-alkenyl)-1,3,2-dioxaborinanes, TETRAHEDR L, 41(42), 2000, pp. 8027-8031
Two simple procedures for obtaining (Z)-2-(1-trimethylsilyl-1-alkenyl)-1,3,
2-dioxaborinanes based on 1-trimethylsilyl-1-alkynes are described. In the
first procedure, 1-trimethylsilyl-1-alkynes are hydroborated with diisopino
campheylborane to provide the corresponding (Z)-2-(trimethylsily1-1-alkenyl
)-diisopinocampheylboranes. These are then reacted with excess acetaldehyde
to afford the corresponding (2)-2-(1-trimethylsilyl-1-alkenyl)-diethoxybor
anes which are esterified with 1,3-propane diol to give the (2)-2-(1-trimet
hylsilyl-1-alkenyl)-1,3,2-dioxaborinanes in good yields and in high stereoc
hemical purities. In the second procedure, 1-trimethylsilyl-1-alkynes are h
ydroborated with dichloroborane-methyl sulfide complex in the presence of a
stoichiometric amount of boron trichloride in hexane, followed by treatmen
t with 1,3-propane diol. These novel stereodefined gem-alkenyldimetaliic co
mpounds containing boron and silicon are isolated and characterized by NMR
(H-1 and C-13) spectral data. (C) 2000 Elsevier Science Ltd. All rights res
erved.