The condensation of Cyclic acetonylphosphonate (II), obtained from bromoacetone and cyclic phosphite (I) by an Arbuzov reaction, with o-nitrobenzaldehyde in the presence of piperidine - AcOH salt in boiling benzene gives benzylidene phosphonale (III), which is cyclized with methyl 3-aminocrotonate (IV) in reflux in 2-propanol affording methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2 oxo-1,3,2-dioxaphosphorinan-2-yl)-1,4 dihydro-pyridine-3 carboxylate.
The reaction of trimethylene glycol (I) with PCl3 gives 2-chloro-1,3,2-dioxaphosphorinane (II), which is condensed with propargyl alcohol (III) by means of triethylamine in acetonitrile to give a mixture of 2-allenyl- and 2-propargyl-2-oxo-1,3,2-dioxaphosphorinane (IV and V). The reaction of this mixture with isobutylamine in acetonitrile affords 2-(2-isobutylamino-1-propenyl)-2-oxo-1,3,2-dioxaphosphorinane (VI). The hydrolysis of the enamine (VI) with malonic acid gives 2-acetonyl-2-oxo-1,3,2-dioxaphosphorinane (VII), which is condensed with isobutyl-(2-nitrobenzylidene)amine (VIII) to yield 2-[1-(2-nitrobenzylidene)-2-oxopropyl]-2-oxo-1,3,2-dioxaphosphorinane (IX). Finally, this compound is cyclized with methyl 3-aminocrotonate (X) in refluxing acetonitrile.