1,2,3-thiadiazoles were synthesized in parallel using a polymer sulfonyl hydrazide resin (PS-TsNHNH2) and employing a "catch and release" synthesis strategy. Resin capture of ketones synthesized from Weinreb amides and Grignard reagents afforded resin-bound sulfonylhydrazones. Cyclizative cleavage of supportbound sulfonylhydrazones with thionyl chloride afforded 1,2,3-thiadiazoles. Excess thion...

Changing course: While organolithium and Grignard reagents favor addition to C1 of A (R=Me), the corresponding organoytterbium reagents add to C2 (R=tBu). Computational studies provide insights into the nature of organoytterbium species and their reactivity, and a total synthesis of (-)-mansonone B illustrates the utility of the method in terpenoid synthesis. Tf=trifluoromethanesulfonyl.

Title of Dissertation: DEVELOPMENT OF ARYL SILOXANE CROSSCOUPLING TECHNOLOGY AND ITS APPLICATION TO THE SYNTHESIS OF COLCHICINE AND ALLOCOLCHICINE DERIVATIVES William Michael Seganish, Doctor of Philosophy, 2005 Dissertation directed by: Professor Philip DeShong Department of Chemistry and Biochemistry One of the most versatile methods for the formation of aryl-aryl bonds is the palladium-catal...

Highly enantioselective synthesis of chiral chromenes and tetrahydroquinolines is achieved by combining asymmetric copper-catalyzed allylic substitution with Grignard reagents and an efficient intramolecular Heck reaction. Moreover, the exocyclic double bond formed in the cyclisation was subjected to RCM, hydroboration and hydrogenation illuminating the synthetic versatility of these heterocycles.

A large-scale synthesis of meso-2,3-difluoro-1,4-butanediol in 5 steps from (Z)-but-2-enediol is described. Crystallographic analysis of the diol and the corresponding benzyl ether reveals an anti conformation of the vicinal difluoride moiety. Monosilylation of the diol is high-yielding but all attempts to achieve chain extension through addition of alkyl Grignard and acetylide nucleophiles fai...

A modular synthetic method for bis- and tris-1,2,3-triazoles that include a benzotriazole structure was developed on the basis of sequential azide-aryne and azide-alkyne cycloadditions. The key to success was efficient halogen-metal exchange reaction-mediated generation of aryne from ortho-iodoaryl triflates bearing a base-sensitive terminal alkyne moiety, which was achieved using trimethylsily...

One-pot stereoselective synthesis of bromohydrins as a useful chiral building block was achieved by the reaction of Grignard reagents with optically active α-bromoaldehydes, which were in situ generated by direct asymmetric bromination of aldehydes catalyzed by a binaphthyl-based secondary amine (S)-3.