Synthesis of the H-phosphonate dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide and the phospha-Michael addition to unsaturated compounds

A series of phosphonate-containing compounds based on dibenzo[d,f][1,3,2]clioxaphosphepine 6-oxide (BPPO) is presented. BPPO is synthesized by a three-component condensation and is added to activated alkenes with systematically varied structure via phospha-Michael addition. Acrylates, alpha,beta-unsaturated carboxylic acid diesters and benzoquinone are used as activated alkenes. The new compounds are characterized by H-1, C-13 and P-31 NMR spectroscopy. The as-prepared phosphonates are envisioned to have flame retardant properties. (C) 2019 Elsevier Ltd. All rights reserved.