Abstract
Continuous recycling of the minor product enantiomer obtained from the acetylcyanation of prochiral aldehydes provided access to highly enantiomerically enriched products. Cyanohydrin derivatives, which under normal conditions are obtained with modest or poor enantiomeric ratios, were formed with high enantiomeric purity by using a reinforcing combination of a chiral Lewis acid catalyst and a biocatalyst. The primarily obtained products were transformed into β-adrenergic antagonists (S)-propanolol, (R)-dichloroisoproterenol, and (R)-pronethalol by means of a two-step procedure.
Keywords:
Lewis acids; aldehydes; beta blockers; biocatalysis; enantioselectivity.
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adrenergic beta-Antagonists / chemical synthesis*
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Adrenergic beta-Antagonists / chemistry
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Adrenergic beta-Antagonists / pharmacology*
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Aldehydes / chemistry*
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Catalysis
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Ethanolamines / chemical synthesis
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Ethanolamines / chemistry
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Ethanolamines / pharmacology
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Isoproterenol / analogs & derivatives
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Isoproterenol / chemical synthesis
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Isoproterenol / chemistry
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Isoproterenol / pharmacology
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Lewis Acids / chemistry
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Molecular Structure
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Nitriles / chemical synthesis*
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Nitriles / chemistry
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Nitriles / pharmacology
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Propranolol / chemical synthesis*
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Propranolol / chemistry
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Propranolol / pharmacology*
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Recycling
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Stereoisomerism
Substances
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Adrenergic beta-Antagonists
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Aldehydes
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Ethanolamines
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Lewis Acids
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Nitriles
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cyanohydrin
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Propranolol
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Isoproterenol
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dichloroisoproterenol
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pronethalol