170 J. Org. Chem. 2011, 76, 170–180 Published on Web 12/10/2010 DOI: 10.1021/jo101858d r 2010 American Chemical Society pubs.acs.org/joc A Palladium-Catalyzed Multicomponent Synthesis of Imidazolinium Salts and Imidazolines from Imines, Acid Chlorides, and Carbon Monoxide Kraig Worrall, Boran Xu, S ebastien Bontemps, and Bruce A. Arndtsen* Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada H3A 2K6 bruce.arndtsen@mcgill.ca Received September 20, 2010 A palladium-catalyzed multicomponent synthesis of imidazolinium carboxylates and imidazolines is described. The palladium catalyst [Pd(CH(R 1 )N(R 2 )COR 3 )Cl] 2 , or [Pd(allyl)Cl] 2 , with P(t-Bu) 2 (2- biphenyl) can mediate the simultaneous coupling of two imines, acid chloride, and carbon monoxide into substituted imidazolinium carboxylates within hours under mild conditions (45 °C, 4 atm of CO). The reaction proceeds in good yield with aryl-, heteroaryl-, and alkyl-substituted acid chlorides, as well as variously functionalized imines. Imidazolines are formed via the initial generation of M€ unchnone intermediates, followed by their cycloaddition with an in situ generated protonated imine. The addition of an amine base can intercept catalysis at M€ unchnone formation, which allows the subsequent cycloaddition of a second imine. The latter provides a route for the assembly of complex, polysubstituted imidazolinium carboxylates with independent control of all five substitu- ents. The subsequent removal of the nitrogen substituent(s) provides an overall synthesis of imidazolines. 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