One-Pot System for Reduction of Epoxides Using NaBH₄, PdCl₂ Catalyst, and Moist Alumina

Abstract

Reduction of epoxides with sodium borohydride, a catalytic amount of palladium(II) chloride, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane gave alcohols in good to excellent yields and good selectivity of the desired products under mild conditions. The reaction system was operationally simple and environmentally friendly. The alumina can be recovered simply and reused a number of times without any treatment and with good activity.

Keywords:

• Epoxide
• moist alumina
• palladium chloride
• reduction
• sodium borohydride

Notes

^a At 40 °C for 3 h; 1a (1 mmol), NaBH₄ (2 mmol), moist alumina (H₂O content, 19 wt.%, 2 g), metal salt (0.1 mmol), and hexane (10 ml) were used.

^b Recovered substrate in mol%.

^a Epoxide (1 mmol) and hexane (10 ml) were used.

^b Moist alumina (H₂O content, 19 wt.%) was used.

^c Isolated yield (mol%).

^d Recovered epoxide in mol%.

^e Ethylbenzene (14%) was formed.

^f 2-Phenylethanol (20%) was formed.

^g 2-(4-Amino-phenyl)ethanol; 4-aminophenylethane (5%) was also formed (see text).