Diisopropylamine → (3S,4R)-1-(t-butyl dimethylsilyl)-3-(1-oxoethyl)-4-[2,2,2-tri(methylthio)ethyl]azetidin-2-one

Temperature

-78 °C

n-Butyllithium (2.43 ml of 2.4 m solution, 5.84 mmol) is added by syringe to a solution of diisopropylamine (591 mg, 5.84 mmol) in 25 ml of freshly distilled tetrahydrofuran at -78° C. The resulting solution is stirred at -78° C. for 15 minutes prior to the addition of a solution of (4R)-1-(t-butyldimethylsilyl)-4-[2,2,2-tri(methylthio)ethyl]azetidin-2-one (1.00 g, 2,85 mmol) in tetrahydrofuran (5 ml). This solution is stirred at -78° C. for 15 minutes, then added via a Teflon tube to a mixture of N-acetylimidazole (642 mg, 5.84 mmol) in 25 ml of THF at -78° C. The resulting yellow reaction mixture is stirred at -78° C. for 10 minutes, then quenched by addition of saturated aqueous ammonium chloride solution. The mixture is diluted with ether (200 ml) and washed with 2.5N hydrochloric acid solution (50 ml), water (50 ml) and brine (50 ml) and dried over magnesium sulfate. Removal of solvents in vacuo gives a yellow oil which is chromatographed on silica gel (30% ether in petroleum ether) to yield (3S, 4R)-1-(t-butyldimethylsilyl)-3-(1-oxoethyl)-4-[2,2,2-tri(methylthio)ethyl]azetidin-2-one. n.m.r. (CDCl3) δ4.42(m, 1), δ4.32(d, 1) δ2.35(m, 2), δ2.32(s, 3), δ2.2(s, 9), δ0.98(s, 9), δ0.3(2s, 6).

1. stirringThis solution is stirred at -78° C. for 15 minutes
2. stirringThe resulting yellow reaction mixture is stirred at -78° C. for 10 minutes
3. customquenched by addition of saturated aqueous ammonium chloride solution
4. additionThe mixture is diluted with ether (200 ml)
5. washwashed with 2.5N hydrochloric acid solution (50 ml), water (50 ml) and brine (50 ml)
6. dry with materialdried over magnesium sulfate
7. customRemoval of solvents in vacuo
8. customgives a yellow oil which
9. customis chromatographed on silica gel (30% ether in petroleum ether)

ORD record

ord-66739f3d8a8f47ae8d617c69506a1cc8

Source dataset

uspto-grants-1988_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04736025