COMPETITIVE REACTIVITY OF THE ARYL ISOTHIOCYANATE DIPOLAROPHILE AT N=C VERSUS C=S WITH NUCLEOPHILIC 1,3-DIPOLES - A COMBINED EXPERIMENTAL AND THEORETICAL-STUDY - THE REACTIONS OF SUBSTITUTED 1,2,3-TRIAZOLIUM-1-AMINIDE 1,3-DIPOLES WITH ARYL ISOTHIOCYANATES - NEW TRICYCLIC THIAZOLO[4,5-D][1,2,3]TRIAZOLES

Substituted 1,2,3-triazolium-1-aminide 1,3-dipoles react with aryl iso thiocyanates at both the N=C and C=S sites to give mixtures of substit uted imidazolo[4,5-d][1,2,3]triazoles and new thiazolo[4,5-d][1,2,3]-t riazoles including tricyclic derivatives with the C-3a and C-6a bridge heads linked via (CH2)(4) and phenanthro groups, The product distribut ion is controlled by the para-substituent of the aryl isothiocyanate, Theoretical calculations, 3-21G and 6-31G*, suggest that linear tripl e bonded canonical forms of the aryl isothiocyanate system play a key role in the ambident reactivity of these systems.