Synthesis of polycyclic phosphonates via an intramolecular Diels-Alder reaction of 2-benzoylbenzalaldehyde and alkenyl phosphites

In this paper, we present a Lewis-acid-promoted reaction of 2-benzoylbenzaldehyde and trialkenyl phosphites, which resulted in the formation of polycyclic phosphonates. The reaction proceeded via nucleophilic attack of trialkenyl phosphite on the carbonyl carbon of 2-benzoylbenzaldehyde. The subsequent intramolecular Diels-Alder reaction led to the formation of the cyclic phosphonate.