ORGANOBORANES. XXV. HYDRIDATION OF DIALKYLHALOBORANES. NEW PRACTICAL SYNTHESES OF DIALKYLBORANES UNDER MILD CONDITIONS

Article abstract of DOI:10.1016/S0022-328X(00)81001-3

Practical methods for the synthesis of dialkylboranes (R2BH) via the hydridation of dialkylhaloboranes (R2BX) have been developed.Convenient methods available for the preparation of R2BX via the hydroboration of alkenes with monohaloborane complexes (H2BX*SMe2) make this approach valuable for the preparation of various dialkylboranes, R2BH, many of which are not available by direct hydroboration of alkenes with borane itself.The suitability of various hydriding agents, such as borane derivatives, complex metal hydrides, and alkoxy metal hydrides, for the hydridationof R2BX was examined, utilizing B-halo-9-borabicyclo<3.3.1>nonane as a representative dialkylhaloborane.In this case, the unusual stability of the resulting dialkylborane, 9-BBN, permits direct estimation of the reaction products by 11B NMR spectroscopy.The generality of the procedure has been demonstrated.