This award supports Professor William C. Agosta of the Rockefeller University for continued collaboration in organic chemistry with Professor Paul Margaretha of the Instiute for Organic Chemistry of the University of Hamburg, Germany. Their joint research focuses on three problems in the chemistry of alkyl propargyl biradicals. One is a mechanistic study of the influence of spin state on the behavior of vinyl carbene intermediates. Another is an extension of their recently discovered (3+2) reaction between alkenes and 3-alkynyl-2-cycloalkenones to intramolecular systems. The final is an exploration of the photochemical cycloaddition of 2-alkynyl-2-cycloalkenones with alkenes, both inter- and intra-molecularly. The two laboratories have complementary strengths and characteristics. Professor Agosta's interests are in the design and synthesis of particular substrates to probe mechanisms and to search for new processes. His small group at The Rockefeller University is composed of postdoctoral workers. Professor Margaretha has particular expertise in chemical theory and radical theory. His research group in Hamburg is much larger than Professor Agosta's and is composed of doctoral students, which makes it better able to carry out studies requiring greater manpower. The long term goals of the above research are to understand better the conditions under which alkyl propargyl biradicals are formed and to define the mechanism of conversion of these biradicals to vinyl carbenes and from them to stable products. Professors Agosta and Margaretha discovered alkyl propargyl biradicals in 1981. Their current and proposed work all involve either new chemistry or novel mechanistic studies in this general area.