Triethylamine → Methyl (2E)(4S)-6-[(3-chloropropyl)sulfonyloxy]-5,5-dimethyl-4-(1,1,2,2-tetramethyl-1-silapropoxy)hex-2-enoate

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Reaction Steps

Following the general procedure for the preparation of neopentyl sulfonylester intermediates of Description 10, 25.7 mL (37.4 g, 211.4 mmol) of 3-chloropropylsulfonyl chloride in 500 mL of anhydrous dichloromethane (DCM) in the presence of 25.8 g (211.4 mmol) of 4-(N,N-dimethylamino)pyridine (DMAP) and 29.5 mL (21.4 g, 211.4 mmol) of triethylamine (Et3N, TEA) was reacted at ca. 0° C. with 40.5 g (133.9 mmol) of methyl (2E)(4S)-6-hydroxy-5,5-dimethyl-4-(1,1,2,2-tetramethyl-1-silapropoxy)hex-2-enoate (4). After work-up and isolation, the crude material was purified by silica gel column chromatography using methyl tert-butyl ether (MTBE) and hexane (Hxn) mixtures (MTBE/Hxn=1:6 MTBE/Hxn=1:5→MTBE/Hxn=1:4) as eluent to provide 50.0 g (84% yield) of the title compound (15a) as a pale-yellow oil. Rf=0.46 (MTBE/Hxn=1:4). 1H NMR (400 MHz, CDCl3): δ=0.01 (s, 3H), 0.09 (s, 3H), 0.93 (s, 9H), 0.97 (s, 3H), 0.98 (s, 3H), 2.30-2.38 (m, 2H), 3.27-3.33 (m, 2H), 3.68-3.73 (m, 2H), 3.77 (s, 3H), 3.98 (d, J=9.6 Hz, 1H), 4.10 (d, J=9.2 Hz, 1H), 4.11 (dd, superimposed, J=6.4, 1.6 Hz, 1H), 5.97 (dd, J=15.6, 1.2 Hz, 1H), 6.90 (dd, J=15.6, 6.8 Hz, 1H) ppm. MS (ESI) m/z 442.9 (M+H)+, 464.9 (M+Na)+. The analytical data was consistent the proposed structure.

Provenance & Evidence