Addition of organometallic nucleophiles to beta-keto phosphonates

The reaction of some Grignard reagents with beta-keto phosphonates results in nucleophilic addition to the carbonyl group to afford beta-hydroxy phosp honates with extension of the carbon skeleton. Additions of allylmagnesium reagents have proven particularly efficient, especially in the presence of BF3. OEt2. Reactions of allylic zinc reagents with beta-keto phosphonates a lso gave the desired beta-hydroxy phosphonates, often in even better yields . With crotyl and prenyl organometallic reagents, the reactions proceed wit h allylic transposition. Because these allylation reactions expand the func tionality of the original substrate, various transformations can be conduct ed on the initial products to provide convenient access to a variety of new phosphonates.