- Regio- and stereoselective synthesis of chiral nitrilolactones using Baeyer–Villiger monooxygenases
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This work describes the regio- and enantioselective synthesis of nitrile-containing chiral lactones from easily accessible ketone precursors using Baeyer–Villiger monooxygenases. These biocatalysts controlled the distribution of regioisomers much more tightly than commonly used stoichiometric reagents, additionally with good to excellent optical purity of products. A surprising case of strong stereoelectronic control was also observed. We tested a library of 14 catalysts using five-to eight-membered cyclic ketones with two different tether lengths to the nitrile group. In all but the largest series we found suitable wild-type enzymes for preparative scale synthesis of the target compounds. The diverse possibilities to further functionalize lactones and nitriles make this method interesting for the generation of chiral building blocks.
- Fink, Michael J.,Snajdrova, Radka,Winninger, Alexander,Mihovilovic, Marko D.
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p. 7241 - 7248
(2016/10/26)
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- Synthesis of 6 H-dibenzo[ b, d ]pyran-6-ones using the inverse electron demand Diels-Alder reaction
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A set of coumarin-fused electron-deficient 1,3-dienes was synthesized, which differ in the nature of the electron-withdrawing group (EWG) at the terminus of the diene unit and (when EWG = CO2Me) the nature and position of substituents. These dienes reacted with the enamine derived from cyclopentanone and pyrrolidine to afford the corresponding cyclopenteno-fused 6H-dibenzo[b,d]pyran-6-ones, most likely via a domino inverse electron demand Diels-Alder (IEDDA)/elimination/transfer hydrogenation sequence. The parent diene (EWG = CO2Me, no substituents) was reacted with a range of electron-rich dienophiles (mostly enamines) to afford the corresponding 6H-dibenzo[b,d]pyran-6-ones or their nondehydrogenated precursors, which were aromatized upon treatment with a suitable oxidant. The enamines could either be synthesized prior to the reaction or generated in situ. The syntheses of 30 dibenzopyranones are reported.
- Pottie, Ian R.,Nandaluru, Penchal Reddy,Benoit, Wendy L.,Miller, David O.,Dawe, Louise N.,Bodwell, Graham J.
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experimental part
p. 9015 - 9030
(2011/12/03)
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- Synthesis and characterisation of medium-sized ring systems by oxidative cleavage. Part 2: Insights from the study of ring expanded analogues
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Variable temperature NMR analysis and computational methods have been used to develop a detailed understanding of the 1H NMR spectra of a family of medium-sized ring containing compounds. The family consists of analogues containing 10-, 11- and
- Lebl, Tomas,Lorion, Magali M.,Jones, Alan M.,Philp, Douglas,Westwood, Nicholas J.
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experimental part
p. 9694 - 9702
(2011/02/23)
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- THE ?-BARRIER TO ROTATION IN STERICALLY UNHINDERED ENAMINES: CONFORMATIONAL STUDIES BY DYNAMIC NMR, XXXVIII
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The ?-barriers to rotation about the enamine (N-Csp2) bond in four pyrrolidinocyclo-n-alkenes (n = 5, 6, 7, 8) have been determined, and are discussed in terms of the steric interactions between the pyrrolidine and cycloalkene rings in the ground state.Distinct barriers were determined for two different conformations of the cyclooctene ring.Barriers were determined in two acyclic N,N-(dialkylamino)cycloalkenes for reference comparison.
- Lunazzi, Lodovico,Casarini, Daniele,Anderson, J.Edgar
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p. 217 - 221
(2007/10/02)
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- NEW GENERAL SYNTHESIS OF MEDIUM RING-LACTONES VIA A REGIOSELECTIVE β-SCISSION OF ALKOXYL RADICALS GENERATED FROM CATACONDENSED LACTOLS
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We describe a new general method for the synthesis of medium-sized lactones based on ring-enlargement via a regioselective β-scission of alkoxyl radicals generated by photolysis from the hypoiodites of several catacondensed lactols.The syntheses of 9-membered lactones from 6/5 fused lactols, 10-menbered lactones including a naturally occuring lactone, phoracantholide I, from 6/6 or 7/5 fused lactols, and 11-membered lactones from 7/6 or 8/5 fused lactols are shown to be achieved by the present method.This new method may have a potential for application to the synthesis of either smaller or larger-sized lactones.
- Suginome, Hiroshi,Yamada, Shinji
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p. 3371 - 3386
(2007/10/02)
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