3-Chloro-2,2-dimethylpropanoyl chloride → p-Nitrobenzyl 2-(4-tert-butylthio-2-oxo-1-azetidinyl)-5-chloro-4,4-dimethyl-3-oxopentanoate

Participants

Reaction Conditions

Reaction Steps

6 ml of a 1M solution of lithium bis(trimethylsilylamide) in THF is slowly added dropwise to a stirred mixture, at 70° C., of 1.06 g (3 mmol) of p-nitrobenzyl 2-(4-tertbutylthio-2-oxo-1-azetidinyl)acetate and 410 μl (3.17 mmol) of chloropivaloyl chloride in 38 ml of absolute tetrahydrofuran, and the mixture is stirred for a further 30 minutes at -70° C. The reaction mixture is diluted with 250 ml of toluene, and 10 ml of 2N aqueous HCl and 100 ml of saturated NaCl solution are added. After separation, the organic phase is again washed with 100 ml of saturated NaCl solution then dried over MgSO4, and filtered, and the solvent is removed in vacuo on a rotary evaporator. The non-crystalline residue is chromatographed over 46 g of silica gel using toluene:ethyl acetate (19:1), to give 980 mg of non-crystalline title compound. IR in CH2Cl2 : 2930, 1770, 1760, 1725, 1615, 1530, 1465, 1370, 1250, 1215, 1190, 1110, 1040, 1000, 847 cm-1.

Provenance & Evidence