The Transition Metal Catalyzed Homo Diels-Alder Reaction

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The transition metal catalyzed [2+2+2] and [4+2+2] homo Diels-Alder reactions of norbornadiene lead to highly caged products with the creation of as many as nine new stereocenters from achiral precursors. Use of chiral bisphosphine ligands imparts significant stereoselectivity to these reactions. The proposed studies focus on the expansion of this chemistry to functionalized dienes and dienophiles and to other homoconjugated dienes, including bicyclo[2.2.2]octadienes. In addition, regiocontrolled cleavage reactions of the caged adducts will be developed, affording access to bicyclic targets. Synthesis of portulal and related diterpenes will illustrate the effectiveness of this methodology.Formation of carbon-carbon bonds represents an essential component of the synthesis of the complex molecules displaying biological or pharmacological activity. Certain classes of reactions result in the formation of multiple carbon-carbon bonds in a single synthetic step, and in addition, such "cycloaddition" reactions are often highly selective, forming only one of many possible isomers of the product. With this award, the Organic Synthesis Program supports the studies of Professor John K. Snyder, of the Department of Chemistry at Boston University. Professor Snyder is developing and exploring the use of an unusual type of cycloaddition reaction for the synthesis of complex polycyclic structures. Additional investigations of the chemistry of these complex structures lead to the development of novel and efficient strategies for organic synthesis, as illustrated by the synthesis of a plant growth regulator, portulal.