Cascade Reaction of Diethyl-(2-Phenylacetyl) Phosphonate with Benzylidene-Malononitrile: Access to Functionalized and Fully Substituted 4H-Pyrans Containing Phosphonate Motif

An efficient DBU-catalyzed Michael-Pinner-isomerization cascade reaction of diethyl-(2-phenylacetyl) phosphonate with 2-benzylidenemalononitrile was developed, and a series of structurally diverse 2-amino-3-cyano-4H-pyrans containing phosphonate functional groups were firstly obtained in up to 98% yields. Moreover, a gram-scale experiment was conducted to demonstrate the synthetic value of this protocol. Also, one-pot three-component cascade reactions of diethyl-(2-phenylacetyl) phosphonates, malononitrile and benzaldehydes were achieved.