Catalytic syn‐Selective Direct Aldol Reactions of Benzophenone Glycine Imine with Aromatic, Heteroaromatic and Aliphatic Aldehydes. Issue 1 (20th November 2014)

• Record Type: Journal Article
• Authors: Lou, Sha; Ramirez, Antonio; Conlon, David A.
• Is Part Of: Advanced synthesis & catalysis. Volume 357:Issue 1(2015)
• Page Start: 28
• Page End: 34
• Publication Date: 2014-11-20
• Subjects: Catalysis -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Chemistry -- Periodicals; Chemistry, Technical -- Periodicals; Chemistry -- Periodicals; Catalysis -- Periodicals; Technology, Pharmaceutical -- Periodicals; 547.2
• DOI: 10.1002/adsc.201400639
• Languages: English
• ISSNs: 1615-4150

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>We have developed highly diastereoselective silver‐catalyzed direct aldol reactions of benzophenone glycine imines with aromatic, heteroaromatic and aliphatic aldehydes. Protection of the secondary alcohol in the aldol product <italic>in situ</italic> with di‐<italic>tert</italic>‐butyl dicarbonate was applied to effectively circumvent the retro‐aldol process resulting in improved yields of the aldol products. Only a catalytic amount of base, lithium <italic>tert</italic>‐butoxide, is required since <italic>tert</italic>‐butoxide is regenerated during the Boc protection. Computational studies support a stereochemical model in which the axially‐oriented nitrogen atom of the imino (<italic>Z</italic>)‐enolates coordinates the silver center in a boat conformation. The highly‐ordered transition states favor the formation of the <italic>syn</italic> aldol products due to the destabilizing interaction between the 1, 3‐pseudoaxial alkoxyl group and the aldehyde substituent in the anti isomer.</p> <p> <boxed-text content-type="graphic" position="anchor" orientation="portrait"> <graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pgh31s3mkwd" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /> </boxed-text> </p> </abstract>