2,2-Dichloropropionyl chloride

Dichloropropionyl chloridefiS was prepared by charging a two liter, 3-necked, roundbottom flask equipped with mechanical stirrer,thermometer, addition funnel, and condenser connected to a caustic scrubber with 250 g of 2,2-dichlorophenoxyacetic acid in 500 ml of chloroform and 10 ml of DMF. The mixture was refluxed for one hour, followed by the addition of 328 g of thionyl chloride over a period of one hour. The mixture was refluxed for two additional hours. After removal of excess thionyl chloride and solvent, the crude product was vacuum distilled yielding 210 g of the acid chloride (b.p. 75°C 20 mm). 

In a typical example (Figure 2), the 2,2-dichloropropionate ester of chitin was prepared by reacting 1.0 g of chitin dissolved in 100 ml of a 5% LiCl/N,N-dimethylacetamide solution with 0.006 moles of 2,2-dichloropropionyl chloride at 140°C for three hours. The product was isolated by precipitation into methanol. 

Preparation. The reagent is obtained in 37% yield by dehydrochlorination of a,/ -dichloropropionyl chloride with diethylaniline. 

Total syntheses of racemic muscarine and allomuscarine were achieved by Pirrung and DeAmicis 11), who used a new approach to formation of the stereoselectively substituted tetrahydrofuran nucleus (Scheme 8). The key step in this procedure was the stereospecific photochemical ring expansion of a cyclobutanone derivative. The cycloaddition of silyl enol ether with methylchloroketene generated by zinc dechlorination of 2,2-dichloropropionyl chloride followed by reductive removal of the halogen produced the methylsiloxycyclobutanone intermediate. Irradiation of the... 

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