Methyl iodide → 5,6-Dihydro-6-methoxy-5,5-dimethyl-7-(2-oxopyrrolidin--1-yl) 7H-thieno[3,2-b]pyran

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Reaction Steps

5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.1 g, 4.11 mmol) was added to a mixture of sodium hydride (60% in mineral oil, 0.172 g, 4.32 mmol) in N,N-dimethylformamide (20 ml) at 0° C. and stirred for 1.5h. Methyl iodide (0.28 ml, 4.52 mmol) was added to the resultant mixture and the mixture stirred at rt for 1h. The mixture was poured into ice water (100 ml) and extracted with dichloromethane. The dichloromethane solution was washed with water (5x) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was crystallized from dichloromethane and hexanes to give the product 0.825 g (71%) as a colorless solid; mp 117°-118° C.; IR(KBr): 2979, 1677, 1572 and 1420 cm-1 ; MS: m/z 282 (MH+); 1H NMR (CDCl3): δ 1.27 (s,3H), 1.48(s,3H), 2.05(m,2H), 2.50(m,2H), 3.33(m,2H), 3.41(d,J=8.8 Hz, 1H), 3.51(s,3H), 5.33(d,J=8.8 Hz, 1H), 6.55(d,J=5.4 Hz, 1H) and 7.09 (d,J=5.4 Hz, 1H).

Provenance & Evidence