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No description available.

A rhodium-catalyzed process has been developed in which mixtures of internal and terminal olefins are isomerized and hydroborated in one step yielding the corresponding terminal pinacolboronates. Homologation and subsequent oxidation regiospecifically affords the terminal aldehyde in what amounts to a one-pot CO free hydroformylation. Good overall yields are obtained in all substrates examined. In a related study, mechanistic aspects of the rhodium catalyzed hydroboration of vinyl arenes have been probed. A combination of substituent effects (Hammett study), deuterium labeling studies and heavy atom isotope effects has demonstrated mechanistic differences in the hydroboration of electron rich and electron poor substrates. The results of the study further demonstrate the differences in reaction mechansim for hydroborations mediated with catecholborane versus pinacolborane. The Corey-Chaykovsky reaction, in which an aldehyde and a sulfur ylide are coupled to yield an epoxide has proven to be a versatile and valuable method for the production of epoxides. The reaction between benzaldehyde and benzyldimethylsulfonium tetrafluoroborate has been subjected to a kinetic analysis. Activation parameters were determined for the reaction and a large negative ΔS‡ of -35 cal/mol/K was calculated for the epoxidation of benzaldehyde. A large carbon kinetic isotope effect of 1.026 and an inverse deuterium isotope effect of 0.93 were determined for the reaction. A large positive Hammett ρ of +2.50 was found for the epoxidation of various substituted benzaldehydes by competition experiments. These results aided in the identification of the rate limiting step as addition of the ylide species to benzaldehyde. In a separate, although related study, the mechanism of the collapse of hydroxysulfonium salts has been examined with regard for implications in the epoxidation of aldehydes. The anti-diastereomer reacted with complete retention of stereochemistry and no crossover, while the syn-diastereomer gave crossover products along with cis and trans epoxides. Deprotonation and re-protonation on the carbon of the alpha-hydroxy sulfonium ylide was responsible for production of the trans epoxide as demonstrated by deuterium labeling. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-08-29 17:56:36.642

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The complexes L(,2)Pt(SR)(,2), where L = PPh(,3), PMePh(,2), PMe(,2)Ph, were prepared in high purity and yield by treating the dichlorides with thiols and triethylamine under nitrogen atmosphere. Their geometry is cis for R = ('n)Pr, ('i)Pr, CH(,2)Ph and trans for R = 4-C(,6)H(,4)Me. Reactions of cis-L(,2)PtCl(,2) and H(,2)S/K(,2)CO(,3) or NaSH in the presence of dichloromethane afforded the complexes L(,2)Pt(S(,2)CH(,2)), containing the novel bidentate methanedithiolato ligand. The thiolato-bridged dimers {LPt(SR')(,2)}(,2), where R' = CH(,2)Ph, 4-C(,6)H(,4)Me, were isolated by fusion of the appropriate monomers in vacuo. The compound {(PMePh(,2))Pt(SCH(,2)Ph)((mu)-SCH(,2)Ph)}(,2) has the cis-symmetrical structure. Treatment of the complexes cis-L(,2)Pt(SCH(,2)Ph)(,2) with phtNSSNpht, where H-Npht = phthalimide, led to stepwise displacement of the phenylmethanethiolato ligands by phthalimido groups. / The first platinadisulfanes, complexes of the type cis-(PPh(,3))(,2)Pt(Npht)(SSR''), where R'' = ('n)Pr, ('i)Pr, CH(,2)Ph, 4-C(,6)H(,4)Me and Npht, were synthesized in good yield by the oxidative addition of R''SSNpht to (PPh(,3))(,2)Pt(C(,2)H(,4)). Similarly, addition of R''SNpht gave cis-(PPh(,3))(,2)Pt(Npht)(SR'').

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Thesis (M.S.)--Ohio University, Novmeber, 1999. / Title from PDF t.p.

Thesis (Ph. D.)--University of Delaware, 2008. / Principal faculty advisor: Charles G. Riordan, Dept. of Chemistry & Biochemistry. Includes bibliographical references.