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.
Key words
triazinanediones - bridgehead-nitrogen heterocycles - N–N bond fragmentation - atom
economy - urazoles