General Procedure for Reduction. A solution of the carboxylic acid (10 mmol) in THF (20 mL) was slowly added to a suspension of NaBHl (12 mmol) in THF (20 mL) at room tem-Derature (10 mid. The mixture was stirred until evolution of gas min) at the temperature mentioned in Table I. Additional hydrogen evolved. The contents were further stirred for 1 h. Dilute HCl (5 mL, 3 N) was added carefully and the mixture extracted with ether. The combined ether ...