Publications by authors named "Madeleine C Warner"

Dynamic kinetic resolution of various homoallylic alcohols with the use of Candida antarctica lipase B and ruthenium catalyst 2 afforded homoallylic acetates in high yields and with high enantioselectivity. These enantiopure acetates were further transformed into homoallylic acrylates after hydrolysis of the ester function and subsequent DMAP-catalyzed esterification with acryloyl chloride. After ring-closing metathesis 5,6-dihydropyran-2-ones were obtained in good yields.

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Cyclopentadienylruthenium complexes commonly serve as efficient transition metal catalysts in the racemization of alcohols. The combination of the racemization reaction with enzymatic resolution leads to dynamic kinetic resolution (DKR). In DKR, a theoretical yield of 100% is possible, making it a powerful tool for enantioselective synthesis.

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A general and efficient route for the synthesis of enantiomerically pure α-substituted ketones and the corresponding lactones has been developed. Ruthenium- and enzyme-catalyzed dynamic kinetic resolution (DKR) with a subsequent Cu-catalyzed α-allylic substitution are the key steps of the route. The α-substituted ketones were obtained in high yields and with excellent enantiomeric excess.

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(13)CO exchange studies of racemization catalyst (η(5)-Ph(5)C(5))Ru(CO)(2)Cl and (η(5)-Ph(5)C(5))Ru(CO)(2)(Ot-Bu) by (13)C NMR spectroscopy are reported. CO exchange for the active catalyst form, (η(5)-Ph(5)C(5))Ru(CO)(2)(Ot-Bu) is approximately 20 times faster than that for the precatalyst (η(5)-Ph(5)C(5))Ru(CO)(2)Cl. An inhibition on the rate of racemization of (S)-1-phenylethanol was observed on addition of CO.

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Reaction of (eta(5)-Ph(5)C(5))Ru(CO)(2)(Ot-Bu) with 5-hexen-2-ol produces two diastereomers of an alkoxycarbonyl complex having the double bond coordinated to ruthenium. The complexes were characterized by (1)H and (13)C NMR spectroscopy and in situ FT-IR measurements. The (13)C NMR carbonyl peaks of the complexes appear at 203.

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