Dimethylformamide → (1R,2R)-2-(ethoxycarbonyl)cyclopropane-1-carboxylic acid

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Reaction Steps

A solution of ethyl 2-formyl-1-cyclopropanecarboxylate (6.465 g, 45.5 mmol) in dry DMF (25 ml) was treated with solid pyridinium dichromate1 (34.23 g, 90.92 mmol, added in ~5 g portions, addition time of 15 min). The resulting mixture was stirred at room temperature for 15 h. After dilution with water (200 ml), the mixture was extracted with ether (5×20 ml) and the combined organic extracts were washed with 1N HCl and brine. The organic phase was then extracted with saturated NaHCO3 (4×20 ml). The basic extracts were acidified with 1-% HCl and extracted with ether (5×20 ml). The combined ether extracts were dried on anhydrous sodium sulfate and evaporated under vacuum to give a clear oil which crystallized on standing: 4.849 g (67%); mp 50-55 (Lit.2 mp 55°-58° C.); ir νmax (CH2Cl2): 3000 (broad OH of acid), 1725 (C=O of ester) and 1700 cm-1 (C=O of acid); 1Hmr (CDCl3) δ: 11.36 (1H, s, COOH), 4.15 (2H, q, J=7, CH2 --CH3), 2.3-1.9 (2H, m, cyclopropyl), 1.5 (2H, d, J=7, cyclopropyl) and 1.27 ppm (3H, t, J=7, CH2 --CH3).

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