Development of organocatalytic 3 2 and 4 2 Cycloadditions Scope and applications

Abstract

Chapter 1 deals with an 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) catalyzed enolatemediated regiospecific synthesis of 1,4,5-trisubstituted N-vinyl-1,2,3-triazoles from simple activated carbonyl compounds and N-vinyl azides through a [3+2]-cycloaddition. Further newlinehydrogenation of these N-vinyl-1,2,3-triazoles led to facile synthesis of 1,4,5-trisubstituted Nalkyl- newline1,2,3-triazoles. newlineChapter 2 presents an enolate mediated strategy for the synthesis of N,N-bicyclic pyrazolidinones by a [3+2]-cycloaddition between and#945;-enolizable aldehydes and cyclic azomethine newlineimines. All the reactions were carried out under DBU or tBuOK catalysis. This chapter expands newlinethe scope of enolate mediate click reactions beyond azides to other 1,3-dipoles like azomethine newlineimines. newlineChapter 3 is an attempt to look at amidines like 1,8-diaza-bicyclo[5.4.0]undec-7-ene (DBU), 1,5-Diazabicyclo(4.3.0)non-5-ene (DBN) and some others in new light not just as catalysts newlineas used extensively in organocatalytic click chemistry, but as substrates in a Lewis acid or selfcatalysed newlineamidine-ynone formal [4+2]-cycloaddition newline