Synthesis of 1,2-silylboranes and silylboronates
An enantioselective silaboration of allenes was achieved using an achiral silylborane in the presence of a palladium catalyst bearing a chiral monodentate phosphine ligand. The enantioselectivity depended on the bulkiness of substituents of allenes.
T. Ohmura, H. Taniguchi, M. Suginome, J. Am. Chem. Soc., 2006, 128, 13682-13683.
A platinum-catalyzed intramolecular silaboration of borylsilanyl homoallyl ethers gave 1-oxa-2-silacyclopentanes in high yields. The stereoselectivity of the reactions strongly depended on the used ligands. A complementary synthesis of a pair of diastereomers of 6-methylheptane-1,3,5-triol is described.
T. Ohmura, H. Furukawa, M. Suginome, J. Am. Chem. Soc., 2006, 128, 13366-13367.
A highly regio- and stereoselective palladium-catalyzed synthesis of various 2-silylallylboronates from allenes and 2-(dimethylphenylsilanyl)-4,4,5,5-tetramethyl[1,3,2]dioxaborolane afforded the corresponding silaboration products in moderate to excellent yields. In the absence of an organic iodide, the silaboration gives products having completely different regiochemistry. In the presence of an aldehyde, the silaboration reaction afforded homoallylic alcohols in one pot in good to excellent yields, with exceedingly high syn selectivity.
K.-J. Chang, D. K. Rayabarapu, F.-Y. Yang, C.-H. Cheng, J. Am. Chem. Soc., 2005, 127, 126-131.