In 1999, he moved to his current position at the University of Pennsylvania where he was promoted to associate professor in 2002 and professor in 2005. Walsh has received several awards, most recent of which was the 2006 Philadelphia Section Award of the ACS. Walsh's interests are in asymmetric reactions, development of new methods, reaction mechanisms, and inorganic chemistry. Hongmei Li received her B.Sc. in chemistry at the Dalian University of Technology in 1999 and her M.Sc. degree in inorganic chemistry (2002) at the Peking University with Professor Jianhua Lin. She began her Ph.D. at the University of Pennsylvania under the direction of Professor Patrick J. Walsh in 2002, during which she worked on the catalytic asymmetric addition of organozinc reagents to ketones and application of bimetallic intermediates in organic synthesis.

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Photolysis of O-neopentyl 5-tributylstannyl dithiocarbonate with hexaphenyl distannane, and 4-methoxyacetophenone as sensitizer, results in crossover of the stannyl groups. The reaction of O-octyl 0'-(2-butoxyethy!) thiocarbonate with tributyltin deuteride or tris(trimetbylsilyl)siiane and a radical initiator shows no significant preference for the cleavage of either C-O bond. Intermolecular competitions between O-octyl O'-phenyl thiocarbonate and 0-(2-butoxyethyl) O'-phenyl thiocarbonate for a deficiency of stannane or silane also indicated no significant preference for reaction of the /3-oxygen-substituted substrate, leading to the conclusion that in conformationally unrestricted systems there is no significant /3-oxygen effect in the Barton deoxygenation reaction. Competition experiments between the cisand frans-0-(4-phenylcyclohexyl) 5-methyl dithiocarbonates and the cisand ;raws-0-(2-phenyli,3-dioxan-5-yl) 5-methyl dithiocarbonates for reaction with tributylstannane reveal that in every case the heterocyclic system is more reactive. The di-isomers of 4-phenylcydohexyl 5-methyl dithiocarbonate and 0-(2-phenyl-1,3dioxan-5-yl) 5-methyl dithiocarbonate, with their axial xanthates, are more reactive than the corresponding transisomers. Molecular mechanics calculations suggest that the greater reactivity of the di-series with respect to the trans is due to the greater relief of strain on fragmentation,

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This Account describes convenient procedures for the preparation of several enantiopure b-amino alcohols and b-diamines, which have proved to be efficient ligands in relevant stereoselective reactions such as alkylation of enolates and hydrogenation of carbonyl compounds. Furthermore, the title compounds are useful precursors of various chiral oxazolidinones, oxazinones, phosphonamides, etc., which allow the enantioselective formation of a wide variety of chiral derivatives, including alcohols, aldol condensation products, aminophosphonic acids, sulfoxides, and others, as well as the development of derivatizing reagents for the determination of enantiomeric purity in chiral alcohols and chiral amines.

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Carotenoids are natural lipophilic pigments and antioxidants that are present in many fruits and vegetables. The consumption of carotenoids is correlated with positive health effects and a decreased risk of several chronic diseases. Provitamin A carotenoids (β-carotene, α-carotene, γ-carotene, and β-cryptoxanthin) are essential for the development and maintenance of sight. β-carotene, α-carotene, zeaxanthin, β-cryptoxanthin, lutein, and lycopene have high antioxidant activity and promote free radical scavenging, which helps protect against chronic diseases. However, carotenoids are chemically unstable and prone to oxidation in the presence of light, heat, oxygen, acids, and metal ions. The use of carotenoids in the food industry is limited due to their poor solubility in water, bioavailability and quick release. Encapsulation techniques, such as microencapsulation, nanoencapsulation and supercritical encapsulation, are used to overcome these problems. The objective of this paper is to describe the characteristics and potential health benefits of carotenoids and advances in encapsulation techniques for protecting and enhancing their solubility or bioavailability.