Synthesis of N–C Fused Bicyclic 1,3,5-Triazinane-2,4-dione Derivatives from Saturated Ring-Fused Urazoles

Abstract A synthesis of novel bicyclic 1,3,5-triazinane-2,4-diones has been accomplished through base-promoted fragmentation followed by cyclization. Various saturated ring-fused bicyclic urazoles were prepared by two complementary methods: by the reaction of N,N′-bis(2-chloroethyl)urazoles with various nucleophiles or by using 4-substituted urazoles and dibromoalkanes. Treatment of these symmetrical urazole derivatives with LDA at –78 °C to 25 °C resulted in fragmentation of the N–N bond to form an imine that underwent intramolecular cyclization, resulting in moderate yields of nonsymmetric heterocycle derivatives with an asymmetric (racemic) center and various ring sizes. The utility of these transformations was extended to syntheses of a tricyclic system and bicyclic systems containing additional heteroatoms.