1-Chloroethyl 1-methylethyl carbonate → HCID 86628908, compound

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Reaction Steps

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) (34.0 g, 89.7 mmol) dissolved in 300 mL of anhydrous toluene was reacted with 30 g (179.5 mmol) of commercially available 1-chloroethyl methylethoxyformate in the presence of 47 g (179.5 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 23.0 g (50% yield) of the title compound (40a). Rf=0.32 (EtOAc/Hxn=1:4). 1H NMR (400 MHz, CDCl3, both diastereomers): δ=1.06-1.08 (m, 6H), 1.24-1.35 (m, 6H), 1.57 (d, J=5.2 Hz, 3H), 2.24-2.31 (m, 2H), 3.20-3.26 (m, 2H), 3.63-3.66 (m, 2H), 3.85-3.86 (2s, 1H), 3.94-3.97 (2d, J=9.6, 9.6 Hz, 1H), 4.19-4.23 (2d, J=9.2, 9.6 Hz, 1H), 4.33-4.38 (2d, J=11.2, 11.6 Hz, 1H), 4.64 (t, J=11.2 Hz, 1H), 4.81-4.97 (m, 1H), 6.81-6.87 (m, 1H), 7.30-7.37 (m, 5H) ppm. MS (ESI) m/z 531.02 (M+Na)+. The analytical data was consistent with the proposed structure.

Provenance & Evidence