Boron trifluoride ctherate

E -a,fi-Unsaturated aldehydes. The anion of 2-alkenyl N,N-diethyldithio-carbamates (2) reacts with (1) at the ce-carbon atom to form a product (a) that undergoes facile [3,3] sigmatropic rearrangement to form (3). The products are hydrolyzed to aldehydes (4) by red mercuric oxide and boron trifluoride ctherate (3, 136). ... 

Z)-2-Butenylpotassium is generated from 4.5 mL (50 mmol) of (Z)-2-butene, 2.8 g (25 mmol) or /-BuOK. and 10.8 mL (25 mmol) oT 2.3 M butyllithium in THF for 15 min at —45 JC. This solution is cooled to — 78 C and 30 mmol of a 1 M solution of methoxy(diisopinocampheyl)borane in diethyl elher is added dropwise. The mixture is stirred for 30 min at — 78 °C, then is treated with 4mL (33 mmol) of boron trifluoride-diethyl ctherate complex this removes methoxide from the intermediate ate complex. This solution is immediatelv treated with 35 mmol of an afdchyde. Isolated yields of homoallylic alcohols are 63-79%. 

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