L-(+)-Cysteine → HCID 18667311, compound

Participants

Reaction Steps

A mixture of cysteine (1.5 g, 12.7 mmol) and the intermediate prepared in Example 2 above, 6-hydroxy-2,5,7,8-tetramethyl-3,4-dihydro-2H-benzo[1,2-b]pyran-2-yl methanal (3.0 g, 13 mmol), in methanol was warmed at reflux for 2.5 h. The reaction mixture was cooled to ambient temperature and then stirred at ambient temperature overnight. The reaction mixture was filtered and the filtrate was recrystallized from ethanol (3 times) to give 1.2 g (28% yield) of (4R)-2-(6-hydroxy-2,5,7,8-tetramethyl-3,4-dihydro-2H-benzo[1,2-b]pyran-2-yl)-4-thiazolidine carboxylic acid as a white solid, m.p. 184°-186° C.

Provenance & Evidence