Azomethine ylides from Delta(1)-1,2,4-triazolines and allylaminomaleates from reactions of allyamines with dimethyl acetylenedicarboxylate

Abstract

<p>The major portion of this thesis deals with the chemistry of 5-t-butyl-3,3-dimethyl-5-methylene-∆¹-1,2,4-triazoline (94) and its derivatives. Triazoline 94, formally also an enamine and an azo compound was treated with several substrates in attempts to synthesize new ∆¹-1,2,4-triazolines suitable for the generation of azomethine ylides. When 94 was treated with heterocumulenes or simple Michael acceptors such as acrylonitrile, the products included highly substituted aziridines (e.g., 109), simple Michael addition products which contain the skeleton of 94, and in one instance, an azabicycloheptene: The reaction of 94 with more-substituted Michael acceptors, methacrylonitrile and methyl methacrylate, yielded 2-t-butyl-iminopyrrolidine derivatives. When 94 was treated with heterocumulenes or simple Michael acceptors such as acrylonitrile, the products included highly substituted aziridines (e.g., 109), simple Michael addition products which contain the skeleton of 94, and in one instance, an azabicycloheptene. The reaction of 94 with more substituted Michael acceptors, methacrylonitrile and methyl methacrylate, yielded 2-t-butyl-iminopyrrolidine derivatives. Spirotriazolines (e.g., 129a) were isolated from the reaction of 94 with benzonitrile oxide and diphenylnitrilimine. The thermal decomposition of these spiro species was found to follow the first order rate law. Treating 94 with phenyl azide and p-nitrophenyl azide provided spiro triazolines whose thermal decomposition involved the loss of two moles of molecular nitrogen. An analog of 94, bearing a fumarato substituent on the exocyclic double bond was found to rearrange to a highly-substituted pyrrole when heated in MeOH. Another analog of 94, this species bearing an anilido substitutent on the exocyclic double bond, was found to lose nitrogen with first order kinetics when heated in MeOH or C₆H₆. In a separate study, allyldimethylaminomaleates (e.g., 177a) resulted from the reactions of allyldimethyl amines with dimethyl acetylenedicarboxylate. The maleates are believed to arise from initial zwitterion formation followed by intramolecular allyl transfer via a evelie 6-membered transition state.</p>