The [4+2] cycloaddition of diethyl 1-phosphonobuta-1,3-diene with tetracyanoethylene,
(E)-1,4-diphenylbut-2-ene-1,4-dione, N-phenylmaleimide, and dialkyl acetylenedicarboxylates is described. For the last two
cases, treatment of the cycloadducts with nitrobenzene and a palladium catalyst allows
the aromatization. Selective deprotections lead to phthalimide/phthalate derivatives
with an ortho-phosphonic acid function.
Key words
cycloaddition - Diels–Alder reaction - phosphorus - bicyclic compounds - carboxylic
acids - hydrolysis