反应详情

Following the general procedure for the preparation of acyloxyalkyl/alkoxycarbonyloxyalkyl carboxylic esters from carboxylic acids of Description 22, (2R)-4-[(3-chloropropyl)sulfonyloxy]-3,3-dimethyl-2-(phenylmethoxy)butanoic acid (11) (0.3 g, 0.79 mmol) dissolved in 5 mL of anhydrous toluene was reacted with 0.58 g (2.4 mmol) of methylethyl (iodomethoxy)formate in the presence of 0.27 g (1.0 mmol) of silver carbonate (Ag2CO3). After work-up, the crude material was purified by silica gel column chromatography using a mixture of ethyl acetate (EtOAc) and hexane (Hxn) (EtOAc/Hxn=1:2) as eluent to provide 0.14 g (36% yield) of the title compound (27a) as a colorless oil. Rf=0.59 (EtOAc/Hxn=1:2). 1H NMR (400 MHz, CDCl3): δ=1.07 (s, 3H), 1.08 (s, 3H), 1.31-1.34 (m, 6H), 2.25-2.32 (m, 2H), 3.32-3.36 (m, 2H), 3.63-3.65 (m, 2H), 3.90 (s, 1H), 3.96 (d, J=9.2 Hz, 1H), 4.21 (d, J=9.6 Hz, 1H), 4.37 (d, J=11.2 Hz, 1H), 4.64 (d, J=11.2 Hz, 1H), 4.89-4.95 (m, 1H), 5.78 (d, J=5.6 Hz, 1H), 5.87 (d, J=5.6 Hz, 1H), 7.30-7.37 (m, 5H) ppm. MS (ESI) m/z 495.02 (M+H)+, 516.98 (M+Na)+. The analytical data was consistent with the proposed structure.

1. customAfter work-up, the crude material was purified by silica gel column chromatography
2. additiona mixture of ethyl acetate (EtOAc) and hexane (Hxn) (EtOAc/Hxn=1:2) as eluent