2-(cyclopentylidenemethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of methylcyclopentane (100 mg, 1.22 mmol), and trans-1-propenylboronic acid pinacol ester (204 mg, 1.22 mmol) in dry dichloromethane (6 mL) was bubbled with nitrogen for 5 minutes. Grubbs Catalyst, 2nd generation (52 mg, 0.06 mmol) was added and the reaction mixture was refluxed overnight. The solution was concentrated in vacuo and the residue was purified by preparative TLC (cyclohexane/ethyl acetate 90/10) to provide 2-(cyclopentylidenemethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (21a) (88 mg, 0.42 mmol, 35%) the reaction mixture was refluxed overnight The solution was concentrated in vacuo the residue was purified by preparative TLC (cyclohexane/ethyl acetate 90/10)