Phosphorus halide free synthesis of 1,2,3,4-tetrahydroisophosphinoline 2-oxides

The herein developed phosphorus halide free synthesis of 1,2,3,4-tetrahydroisophosphinoline 2-oxides involves intramolecular heterocyclization of P,P-bis(2-arylethyl)-P-(α-hydroxybenzyl) phosphine oxides, available from styrenes, phosphine and aldehydes. The cyclization proceeds in the presence of FeCl₃ at 80°C, yield of the products is 53–60%.