3,595 research outputs found

    Phosphine-Catalyzed Formation of Carbon-Sulfur Bonds: Catalytic Asymmetric Synthesis of gamma-Thioesters

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    Supporting Information Available: Experimental procedures and compound characterization data. This material is available free of charge via the Internet at http://pubs.acs.org.A method for catalytic asymmetric Îł sulfenylation of carbonyl compounds has been developed. In the presence of an appropriate catalyst, thiols not only add to the Îł position of allenoates, overcoming their propensity to add to the ÎČ position in the absence of a catalyst, but do so with very good enantioselectivity. Sulfur nucleophiles are now added to the three families of nucleophiles (carbon, nitrogen, and oxygen) that had earlier been shown to participate in catalyzed Îł additions. The phosphine catalyst of choice, TangPhos, had previously only been employed as a chiral ligand for transition metals, not as an efficient enantioselective nucleophilic catalyst.National Institutes of Health (U.S.)National Institute of General Medical Sciences (U.S.) (R01-GM57034)Merck & Co.Novartis (Firm

    A Guide to Directing Group Removal: 8‐Aminoquinoline

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    The use of directing groups allows high levels of selectivity to be achieved in transition metal‐catalyzed transformations. Efficient removal of these auxiliaries after successful functionalization, however, can be very challenging. This review provides a critical overview of strategies used for removal of Daugulis’ 8‐aminoquinoline (2005–2020), one of the most widely used N,N‐bidentate directing groups. The limitations of these strategies are discussed and alternative approaches are suggested for challenging substrates. Our aim is to provide a comprehensive end‐users’ guide for chemists in academia and industry who want to harness the synthetic power of directing groups—and be able to remove them from their final products

    Coherent states for polynomial su(1,1) algebra and a conditionally solvable system

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    In a previous paper [{\it J. Phys. A: Math. Theor.} {\bf 40} (2007) 11105], we constructed a class of coherent states for a polynomially deformed su(2)su(2) algebra. In this paper, we first prepare the discrete representations of the nonlinearly deformed su(1,1)su(1,1) algebra. Then we extend the previous procedure to construct a discrete class of coherent states for a polynomial su(1,1) algebra which contains the Barut-Girardello set and the Perelomov set of the SU(1,1) coherent states as special cases. We also construct coherent states for the cubic algebra related to the conditionally solvable radial oscillator problem.Comment: 2 figure
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