The remarkable versatility and selectivity of the 10-(trimethylsilyl)-9-borabicyclo [3.3. 2] decanes (10-TMS-9-BBDs) in the allyl-and crotylboration of representative aldehydes are reported. The new reagents are prepared through air-stable crystalline pseudoephedrine borinic ester complexes of the 10-TMS-9-BBDs (4), which are available in 63% overall yield from B-MeO-9-BBN through a simple two-step procedure. These complexes 4 are directly ...