Benzo(B)Thiophene → 2-(Dimethoxyacetyl)benzothiophene

Participants

Reaction Steps

A solution of benzothiophene (7.11 g., 0.053 mol) in 120 ml. dry THF was cooled to 0°. Butyl lithium (35.3 ml. of 1.5M in hexane, 0.053 mol) was added dropwise, maintaining 0°-5°, and the mixture then warmed to ambient temperature for 1.25 hours, cooled to -75° C. and N-(dimethoxyacetyl)morpholine (10.0 g., 0.053 mol) in 50 ml. dry THF added dropwise maintaining -75° to -70°. The reaction was quenched by adding to 300 ml. saturated NH4Cl and 300 ml. ether. The organic layer was separated, washed with brine, dried over MgSO4 and stripped to an oil, 14 g., which was distilled to yield purified title product, 8.00 g., bp 137°-139°/0.25 mm.; tlc Rf 0.23 (6:1 hexane:ethyl acetate), 0.47 (2:1 hexane:ethyl acetate); 1H-nmr 3.6 (s, 6H), 5.2 (s, 1H), 7.3-7.6 (m, 2H), 7.8-8.05 (m, 2H), 8.4 (s, 1H), tlc Rf 0.31 (4:1 hexane:ethyl acetate), 0.47 (2:1 hexane:ethyl acetate).

Provenance & Evidence