Phosphonates, allenic reaction with allylic alcohols

The intermediate product 162, formed from the nudeophilic addition of 1,2-alle-nic phosphonate or 1,2-allenic phosphine oxide with allylic alcohol, would also undergo a Claisen rearrangement to form 2-oxo-5-alkenyl phosphonate or phosphine oxide 163 [85], The rearrangement is accelerated by the carbanionic nature of the intermediate 162. For the conjugate addition step, the reaction temperature is crucial since the reaction at 0 °C afforded mainly /i,y-unsaturated product whereas a,/8-unsaturated products were formed at 20 °C. 

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. ... 

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