Phosgene → 3-(2-Chloro-6-methylphenoxy)-1-azetidinecarbonyl chloride

A mixture of 13.9 g (0.14 mole) of phosgene and 17.3 g (0.125 mole) of potassium carbonate in 140 mL of methylene chloride was stirred under nitrogen for 30 min then cooled in an ice water bath while 46.5 g (0.125 mole) of 3-(2-chloro-6-methylphenoxy)-1-(diphenylmethyl)azetidine in 140 mL of methylene chloride was added dropwise. After stirring for 16 h the excess phosgene was destroyed by adding small pieces of ice. Water was added to dissolve the inorganic material and the methylene chloride portion was separated, dried (filtered through Whatman PS paper) and concentrated in vacuo, 65.8 g. The oily residue was triturated with 300 mL of 30/60 pet ether and then with 300 mL of hexanes, both at ambient temperature. The remaining yellow residue was triturated with boiling hexanes and the hot solution decanted (4×200 mL). Upon cooling an orange oil separated which was removed from the hexanes solution by decanting. After decanting again, the hexanes solution was cooled in an ice bath and decanted to remove all traces of the impure orange oil. The volume of hexanes was reduced to 75 mL by heating under a stream of nitrogen. Upon cooling, crystalline product was obtained in 2 fractions (10.8 g and 5.5 g). Rework of the filtrate and the ambient temperature filtrates (300 mL of pet ether and 300 mL of hexanes) yielded an additional 6 g of product for a total yield 22.3 g crude (68.6%), mp 67°-69° . A sample was recrystallized for analysis from hexanes, mp 70°-71.5° C.