Title : Functionalization of N-Heterocycles in Transition Metal Catalyzed Reactions
There are several ways of introducing acyl functionality into simple model compounds or skeletons of practical importance. The application of conventional acylating agents is well known and is referenced in reviews, handbooks and even textbooks. Since the discovery of the aminocarbonylation by Heck et al (‘Heck-carbonylation’),1 the use of a primary or secondary amine, carbon monoxide and aryl/alkenyl halides (or their synthetic surrogates, aryl triflates and alkenyl triflates) in the presence of palladium catalysts lead to carboxamides in great variety.2
Our presentation will be focused on the following topics:
- The efficiency of palladium(II)-acyl intermediates, formed via carbon monoxide insertion into Pd-aryl/alkenyl bonds, as acylating agents will be exemplified.
- The reaction mechanism will be rationalised on the basis of a catalytic cycle.
- High-yielding palladium-catalysed aminocarbonylation of functionalised iodoaromatics and iodoalkenes towards carboxamides (via single CO insertion) and 2-ketocarboxamides (via double CO insertion) will be discussed. The functional group tolerance of the palladium-catalysed reaction will be shown.
- The synthesis of compounds of pharmacological importance (penicillins, cephalosporins, etc.) will be discussed by choosing more complicated skeletons as N-nucleophiles in aminocarbonylation.
- The efficiency of the combination of high-yielding conventional reactions and highly selective homogeneous catalytic reactions will be shown in multistep syntheses under green conditions.