Triethylamine → (4S)-1-(t-butyldimethylsilyl)-4-iodomethyl-azetidin-2-one

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Reaction Steps

t-butyldimethylchlorosilane (7.51 g, 49.8 mmol) is added in one portion to an ice-cold, stirring solution of (4S)-4-iodomethyl-azetidin-2-one (10.0 g, 47.4 mmol) and triethylamine (5.04 g, 49.8 mmol) in anhydrous dimethylformamide (100 ml). A voluminous white precipitate forms almost immediately. The reaction mixture is stirred at 0°-5° for 1 hour and then allowed to warm to room temperature. Most of the solvent is removed under vacuum to give a residue which is partitioned between diethyl ether (250 ml) and water. The ethereal phase is washed with 2.5 N hydrochloride acid (50 ml), water (3×50 ml), and brine, dried with magnesium sulfate, filtered, and evaporated under vacuum to provide (4S)-1-(t-butyldimethylsilyl)-4-iodomethyl-azetidin-2-one (15.1 g) as a white solid. Recrystallization from petroleum ether-ethyl ether gives the product as colorless plates, mp 71°-72°; n.m.r. (CDCl3), δ3.8(m,l), δ2.6-3.6 (2 overlapping d of AB, 4) δ1.0 (S,9), δ0.3(S,6), δ0.25(S,6).

Provenance & Evidence