4 pages, 1 figure, 1 table, 1 scheme.-- PMID: 15675866 [PubMed].-- Printed version published Feb 4, 2005.Supporting information available: Spectroscopic and analytical data for compounds 3c-j.-- Available at: http://pubs.acs.org/doi/suppl/10.1021/jo048469qA modular, one-pot, two-step, four-component synthesis of polysubstituted 1,3-oxzolidines is described. The method comprises two linked domino processes: an organocatalyzed domino reaction of alkyl propiolate and an aliphatic aldehydes and a microwave-assisted amine addition cyclization domino process. An alternative modular, one-pot, three-step, four-component synthesis has also been developed by linking the organocatalyzed domino process to a sequential amine addition/Yb(OTf)3-catalyzed enamine cyclization reaction.This research was supported by the Spanish Ministerio de Educación y Ciencia (PPQ-2002-04361-C04-03). D.G.C. thanks the Spanish Ministerio de Educación y Ciencia for a FPI grant. F.G.T. and D.T. thank the Instituto Canario de Investigación del Cáncer for financial support (ICIC-PI. No. 07/2004; ISCIII, RTICCC C03/10)