Reactions with OH Groups and Epoxides

Reactions with —OH Groups and Epoxides.—The formation of A -l,2-oxaphos-pholen derivatives from propargylic alcohols and phosphorus trichloride has been studied in detail. Intermediate phosphites (24) and allenic phosphonates (25) are described, and the A -l,2-oxaphosphoIen is produced in the final stage, as shown. Improved conditions have been outlined for the preparation of allylic bromides (26) from allylic alcohols and phosphorus tribromide. Related reactions of primary alcohols with the complex of phosphorus trichloride and DMF lead to the chloride (27) 22 addition of zinc bromide to the reaction results in the formation of alkyl bromides, but an attempt to extend this exchange to the preparation of cyanides was not successful.  

Base-catalysed condensation of a-hydroxycarboximidic esters (32) with phosphorus trichloride yields the new heterocycles (33), although minimal evidence has been presented in support of the structure assignment.  

A number of examples of reactions of chlorophosphines with ethylene oxide have been published. Thus the phosphines (34)—(36) are each converted into P chloroethoxy-derivatives, presumably by nucleophilic attack at phosphorus by the epoxide oxygen. 

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