1-Chloro-(2-methylpropyl) (methylethoxy)formate → 2-Methyl-1-(methylethoxycarbonyloxy)propyl (2R)-4-[(3-chloropropyl)sulfonyloxy]-3,3-dimethyl-2-(1,1,2,2-tetramethyl-1-silapropoxy)butanoate

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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-(1,1,2,2-tetramethyl-1-silapropoxy)butanoic acid (15) (0.4 g, 0.99 mmol) dissolved in 5 mL of anhydrous toluene was reacted with 0.57 g (3.0 mmol) of 1-chloro-(2-methylpropyl) (methylethoxy)formate in the presence of 0.33 g (1.1 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 0.37 g of a mixture of the title compound (47a) and (3R)-4,4-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)-3,4,5-trihydrofuran-2-one (4a). MS (ESI) m/z 583.12 (M+Na)+.

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