title: Minor enantiomer recycling: application to enantioselective syntheses of beta blockers.
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.
authors.affiliation: KTH Royal Institute of Technology, Department of Chemistry, Organic Chemistry, 10044 Stockholm (Sweden).
authors.forename: Ye-Qian
authors.initials: YQ
authors.lastname: Wen
authors.forename: Robin
authors.initials: R
authors.lastname: Hertzberg
authors.forename: Inanllely
authors.initials: I
authors.lastname: Gonzalez
authors.forename: Christina
authors.initials: C
authors.lastname: Moberg
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D004983:Ethanolamines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D007545:Isoproterenol / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D058116:Lewis Acids / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011433:Propranolol / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D059027:Recycling; D013237:Stereoisomerism
chemical_list: D000319:Adrenergic beta-Antagonists; D000447:Aldehydes; D004983:Ethanolamines; D058116:Lewis Acids; D009570:Nitriles; C430593:cyanohydrin; D011433:Propranolol; D007545:Isoproterenol; C084581:dichloroisoproterenol; C084832:pronethalol
keywords: Lewis acids; aldehydes; beta blockers; biocatalysis; enantioselectivity