New tandem reactions for the construction of heterocycles via dianion strategy

Abstract

The reaction of chiral and achiral salen ditopic ligands with sodium in dry isopropanol generates remote O,O-dianions. The dianions thus generated in situ are trapped by suitable phosphorus dielectrophiles to yield 2-oxo and 2-thioxo-1,3,7-dioxazaphos-phadecines and 2-oxo and 2-thioxo-1,3,7,10- dioxadiazaphos-phatridecines in moderate to good overall yield. The products are characterized by elemental and spectral (1R, 1H. 13C, 31P NMR and Mass) studies. A plausible mechanistic logic and concept utilized in the synthesis have been discussed.