Nitric Acid → 5,6-Dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran

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Reaction Steps

Nitric acid (90%, 1.2 mL, 26.9 mmol) was added to a solution of 5,6- dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.0 g, 3.74 mmol) in acetic acid (30 mL) at 18° C., and stirred at rt for 1.5 h. The resultant solution was poured into ice water (200 mL). Within 10 min a yellow solid crystallized which was collected by filtration, washed with water and triturated in diethyl ether to give the product, 0.487 g (42%), as a yellow solid: mp 214°-217° C.; IR (KBr): 3216, 1655 and 1512 cm-1 ; MS: m/z 313 (MH+); 1H NMR

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