1085at -50 "C to yield 124 mg (41%) of 2 after flash chromatography; GC (5.3 min, 10%; 5.9 mim, 90%).Method B was performed on 23.2 mg (0.163 mmol) of 5 with 0.17 mL (0.170 mmol) of catechol borane (1.0 M in THF) and 10.0 mL (0.016 M) of dichloromethane at -78 O C to yield 20.0 mg (85%) of 2 after flash chromatography; GC (5,3 min, 29%; 5.9 min, 71%).
re1 -( 2 S ,5R ,aS )-a-Ethyl-5-methyltetrahydrofuran-methanol (4). Method B was performed on 29.7 mg (0.209 mmol) of 6 with 0.21 mL (0.210 mmol) of Me2S-BH3 (1.0 M in dichloromethane) and 42 mL (0.005 M) of dichloromethane to yield 22.9 mg (67%) of crude 4, and flash chromatography produced 10.5 mg (35%) of 4 as a clear colorless oil. 4 ' H NMR (250 MHz, CDC13) 6 4.07 (app hextet, J = 6.0 Hz, 1 H, H-5), 3.85 (app q, J = 7.0 Hz, 1 H, H-2), 3.32 (m, H-a), 2.03 (m, 2 H), 1.70-1.37 (m, IR 3600-3400,2980,2940,2880,1470,1380,990 cm-'; TLC (2:2:1 hexane-CHzClz-ethyl acetate, Rf0.32); GC (5.2 min, 6;% 5.7 min, 94%). The 13C NMR data was the same as reported in ref 4. Method B was performed on 33.2 mg (0.234 mmol) of 6 with 0.23 mL (0.230 mmol) of Me$-BH3 (1.0 M in dichloromethane) and 13.0 mL (0.018 M) of dichloromethane at -50 O C to yield 26.7 mg (79%) of crude 4; GC (5.2 min, 11%; 5.7 min, 89%).Acknowledgment. Financial support from NSF (CHE 8713080) is gratefully acknowledged.Registry No.