Trimethylamine oxide → Isobutylene

Participants

Reaction Conditions

Reaction Steps

Diisopinocampheylborane was prepared by the method of H. C. Brown et al., Israel J. Chem. 15, 12 (1977) from (+)-α-pinene. To the stirred suspension of diisopinocampheylborane (25 mmol) in tetrahydrofuran at -25° C. was added dropwise 2.4 mL (25 mmol) of 1,3-cyclohexadiene. Monohydroboration of the diene was complete after stirring the reaction mixture at -25° C. for 12 hours, as indicated by the disappearance of the solid diisopinocampheylborane and 11B NMR (δ+80) examination of the solution. The reaction mixture was oxidized with trimethylamine-N-oxide, giving a 92:8 mixture of (-)-2-cyclohexen-1-ol (94% ee) and 3-cyclohexen-1-ol. A second reaction mixture at -78° C. was treated with 25 mm of lithium tert-butyl. Isobutylene was formed and the organoborane was converted into the corresponding borohydride as represented by the following reaction scheme.

Provenance & Evidence