Pseudoephedrine → (4S,5S)-2-Allyl-2-chloro-3,4-dimethyl-5-phenyl-1-oxa-3-aza-2-silacyclopentane

Participants

Reaction Steps

To a cooled (0° C.) solution of allyltrichlorosilane (101 mL, 0.696 mol) in methylene chloride (1.8 L) under argon was added triethylamine (170 mL, 1.21 mol). (1S,2S)-pseudoephedrine (100 g, 0.605 mol) was then added portionwise over 30 min, to maintain internal temperature below 15° C. After the addition was complete the mixture was stirred for 12 hours at ambient temperature. The methylene chloride was removed by distillation and the residue was diluted with pentane (1.5 L). The mixture was vigorously stirred for 12 hours to ensure complete precipitation of the triethylamine salts. Filtration of the resulting suspension through a pad of celite and concentration of the filtrate by distillation afforded the crude product as a pale yellow oil. Purification by distillation under reduced pressure (bp˜120 C, 5 mm Hg) provided 149 g (92%) of (4S, 5S)-2-Allyl-2-chloro-3,4-dimethyl-5-phenyl-[1,3,2]oxazasilolidine as a ˜2:1 mixture of diastereomers.

Provenance & Evidence