Triethylamine → Methyl (2E)(4S)-6-{[3-(acetylamino)propyl]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, N-[3-(chlorosulfonyl)propyl]acetamide (9) (4.0 g, 19.8 mmol) in 40 mL of dichloromethane (DCM) in the presence of 1.2 g (9.8 mmol) of 4-(N,N-dimethylamino)pyridine (DMAP) and 2.8 mL (2.0 g, 19-8 mmol) of triethylamine (Et3N, TEA) was reacted at ca. 0° C. with 3.0 g (9.9 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 ethyl acetate (EtOAc) and methanol (MeOH) mixtures (EtOAc/MeOH=9:1) to provide 2.5 g (55% yield) the title compound (19a) as a colorless oil. Rf=0.46 (EtOAc). 1H NMR (400 MHz, CDCl3): δ=0.01 (s, 3H), 0.08 (s, 3H), 0.93 (s, 9H), 0.97 (s, 6H), 2.06 (s, 3H) 2.07-2.11 (m, 2H), 3.14-3.18 (m, 2H), 3.40-3.45 (m, 2H), 3.77 (s, 3H), 3.98 (d, J=9.6 Hz, 1H), 4.06 (d, J=9.2 Hz, 1H), 4.09 (dd, superimposed, J=6.4, 1.6 Hz, 1H), 5.93 (br., 1H), 5.96 (dd, J=15.6, 1H), 6.90 (dd, J=15.6, 6.4 Hz, 1H) ppm. MS (ESI) m/z 466.10 (M+H)+. The analytical data was consistent with the proposed structure.

Provenance & Evidence