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Recyclable Cu(II)-macrocyclic salen complexes catalyzed nitroaldol reaction of aldehydes: A practical strategy in the preparation of (R)-phenylephrine

Paper ID Volume ID Publish Year Pages File Format Full-Text
40647 45861 2012 6 PDF Available
Title
Recyclable Cu(II)-macrocyclic salen complexes catalyzed nitroaldol reaction of aldehydes: A practical strategy in the preparation of (R)-phenylephrine
Abstract

Chiral macrocyclic salen ligands 1′–3′ derived from 1R,2R-(−)-1,2-diaminocyclohexane, 1R,2R-(+)-1,2-diphenyl-1,2-diaminoethane and (R)-(+)-1,1′-binaphthyl-2,2′-diamine with trigol bis aldehyde were prepared and characterized by microanalysis, 1H NMR, UV/Vis. spectroscopy, optical rotation and mass spectroscopy. Highly enantioselective nitroaldol reaction of various aromatic and aliphatic aldehydes with nitromethane in presence of several bases were carried out in the presence of in situ generated Cu(I)/Cu(II) complexes with chiral macrocyclic salen ligands 1′–3′ at RT. Excellent yields (up to 92% with respect to the aldehyde) of β-nitroalcohols with high enantioselectivity (ee, ∼95%) was achieved in case of 3-methoxy- and 4-nitrobenzaldehyde in ca. 30 h with the use of chiral macrocyclic salen ligands 3′ with CuCl2·2H2O in presence of 2,6-lutidine as a base. Chiral macrocyclic salen catalyst 3 mediated nitroaldol process is recyclable (up to 8 cycles with no significant loss in its performance). This protocol is also used for the synthesis of enantiomerically pure (R)-phenylephrine (α1-adrenergic receptor agonist) via asymmetric nitroaldol reaction of 3-methoxybenzaldehyde in three steps.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (146 K)Download as PowerPoint slideHighlights► Chiral Cu(II) macrocyclic salen catalysts with trigol linker were designed. ► These complexes were used for asymmetric nitroaldol reaction of aldehydes. ► β-nitroalcohols were achieved in high yield (92%) with 95% ee in 30 h at RT. ► This protocol is used for the synthesis of (R) phenylephrine in high yield and ee. ► The catalyst worked well up to 8 cycles with retention of catalyst performance.

Keywords
Enantioselective; Chiral Cu(II) macrocyclic complex; Chiral β-nitroalcohols; Aldehydes; Recyclable
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Recyclable Cu(II)-macrocyclic salen complexes catalyzed nitroaldol reaction of aldehydes: A practical strategy in the preparation of (R)-phenylephrine
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 439–440, 10 October 2012, Pages 74–79
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us