Development of novel carbon-carbon bond-forming reactions using α-phospnonovinyl carbanions

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We note the following results from this research :(1) By using the β-heteroatom substituted vinylphosphonates, we succeeded in preparation of the novel α-phosphonovinyl carbanions, which were stabilized with steric hindrance and electron donating ability of β-heteroatom-substituents. Only a limited number of methods have been reported for the preparation of α-phosphonovinyl carbanions due to their lability. These results would be an approach to solve this problem.(2) α-Lithiated vinylphosphonates were easily reacted with various electrophiles to give corresponding α-functionalized(R_3Sn, R_3Si, I) vinylphosphonates. Furthermore, we showed that the effect of additive such as Lewis acid and metal salt in this reaction. These results have indicated that these α-phosphonovinyl carbanions can serve a effective method for synthesis of multi-functionalized phosphorus compounds.(3) It was found that α-silylated phosphonoketene dithioacetals were applied to Friedel-Crafts acylation due to catio … More n stabilizing effect of silyl and thio groups in the molecule. Moreover, α-silyl-β-(ethoxy)vinylphosphonate successfully underwent nuvleophilic substitution to afford β-substituted vinylphosphonate. These results demonstrates that nublephilic additon-elimination reaction could be applicable to functionalization at β-position of vinylphosphonates.(4) Synthetic utilization of α-(triorganometal)- or iodo-substituted vinylphosphonates as heteroatom-substituted olefins was performed. It was found that α-silylated phosphonoketene dithioacetals were applied to Friedel-Crafts acylation due to cation stabilizing effect of silyl and thio groups in the molecule. Moreover, α-silyl-β-(ethoxy)vinylphosphonate sucessfully underwent nucleophilic substitution to afford β-substituted vinylphosphonate. These results demonstrates that nucleophilic addition-elimination reaction could be applicable to functionalization at β-position of vinylphosphonates. We achieved palladium-catalyzed cross-coupling reaction of α-stannyl and iodo-substituted vinylphosphonates and the successive C-C bond formation. These methods open a new way to synthesis of α-alkenyl and alkynylphosphonates. Less