Synthesis of some novel spiro heterocycles

摘要

A new class of spiro pyrimidinetriones,thioxopyrimidinediones,pyrazolidinedioncs and isoxazolidinediones are prepared from dihydro pyridine/pyran/thiopyran dicarboxylates.During the last one decade we have been engaged in the synthesis of spiro heterocycles by exploiting gem-diester functionalities.In our endeavor to search for simple,multifunctional reactive intermediates,3,3-disubstituted-1,5-diaryl-1,5-pentanediones have been chosen.