Water → Ditert-butyl (2S,5S)-5-vinylpyrrolidine-1,2-dicarboxylate

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Reaction Steps

93.5 ml (61.69 mmol, 2.0 eq) of a solution of KHMDS in toluene (15 w %, ABCR) was added under argon at RT to a suspension of 22.037 g (61.69 mmol, 2.0 eq) Ph3PMeBr in 220 ml THF, and the substance was stirred for 1 h. Then, a solution of 9.234 g (30.88 mmol, 1.0 eq) of the aldehyde 111 in 70 ml THF was dropped in at −78° C., and the resulting solution was stirred for 2.5 h at RT. 160 ml saturated Rochelle salt solution and 100 ml water was added to the reaction mixture, then extracted 3× with 260 ml MTBE each, the combined organic phases were washed with saturated NaCl solution and dried over magnesium sulfate. The solvent was removed at reduced pressure and, after purification by means of column chromatography on silica gel with EtOAc/CyHex (1:9) as eluent, 8.091 g (27.21 mmol, 88%) of the vinyl proline 112 was obtained as an isomeric mixture (d.r.: 1.7:1 cis:trans).

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