Enantioselective One‐Pot Catalytic Synthesis of 4, 5‐Epoxy‐3‐alkanols and 1‐Phenyl‐2, 3‐epoxy‐1‐alkanols from α, β‐Unsaturated Aldehydes. Issue 22 (25th June 2013)

• Record Type: Journal Article
• Authors: Infante, Rebeca; Hernández, Yulan; Nieto, Javier; Andrés, Celia
• Is Part Of: European journal of organic chemistry. Issue 22(2013)
• Page Start: 4863
• Page End: 4869
• Publication Date: 2013-06-25
• Subjects: Allylic compounds -- Aldehydes -- Asymmetric synthesis -- Epoxides -- Zinc; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201300397
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: Conformationally restricted perhydrobenzoxazines have been demonstrated to be good chiral ligands for one‐pot asymmetric ethylation/epoxidation, and the unprecedented arylation/epoxidation of trisubstituted α, β‐unsaturated aldehydes. The scope of the reaction has been studied and a wide set of substrates with allylic strain of different nature has been explored, obtaining good or total diastereoselectivities in all cases. The enantiocontrol was good or high for the ethylation/epoxidation reaction, whereas it remained at moderate or good levels for the arylation/epoxidation. The reaction is general for trisubstituted enals, and alkylic and aromatic substituents are tolerated at both the α‐ and β‐position of the unsaturated aldehyde; however, disubstituted enals remain challenging substrates. When the one‐pot and two‐pot protocols were compared, no significant differences concerning the stereocontrol were found, so the advantages of the one‐pot procedure are clear. Abstract : An asymmetric one‐pot phenylation/epoxidation is reported, involving the preparation of the arylating species in situ, further addition to the unsaturated aldehyde employing an enantiopure perhydrobenzoxazine, followed by epoxidation to yield chiral 1‐phenyl‐2, 3‐epoxy‐1‐alkanols.