1-Alkoxymethylvinylphosphonates 3a-e have been synthesized by piperidine catalyzed condensation of diethylphosphonoacetic acid 1 with paraformaldehyde in the presence of various primary and secondary alcohols. Similar reaction of the acid 1 with paraformaldehyde and sorbic alcohol 3f afforded a mixture of three bicyclic compounds 7, 9 and 11 in a ratio 2:1:1, respectively. The latter results strongly evidence the intermediacy of phosphonoacrylic acid 4 in the condensation. Under analogous conditions the olefin 14 was obtained from the acid (E,Z)-13.
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Henryk Krawczyk (1996) studied this question.
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