Efficient Access to All‐Carbon Quaternary and Tertiary α‐Functionalized Homoallyl‐type Aldehydes from Ketones. Issue 41 (1st September 2017)

• Record Type: Journal Article
• Authors: Pace, Vittorio; Castoldi, Laura; Mazzeo, Eugenia; Rui, Marta; Langer, Thierry; Holzer, Wolfgang
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 41(2017)
• Page Start: 12677
• Page End: 12682
• Publication Date: 2017-09-01
• Subjects: aldehydes -- carbenoids -- enolates -- homologation -- isomerization; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201706236
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: β, γ‐Unsaturated aldehydes with all‐carbon quaternary or tertiary α‐centers were rapidly assembled from ketones through a unique synthetic operation consisting of 1) C1 homologation, 2) Lewis acid mediated epoxide–aldehyde isomerization, and 3) electrophilic trapping. The synthetic equivalence of a vinyl oxirane and a β, γ‐unsaturated aldehyde is the key concept of this previously undisclosed tactic. Mechanistic studies and labeling experiments suggest that an aldehyde enolate is a crucial intermediate. The homologating carbenoid formation plays a critical role in determining the chemoselectivity. Abstract : Three in one : β, γ‐Unsaturated aldehydes with all‐carbon quaternary or tertiary α‐centers were rapidly assembled from ketones through a unique synthetic operation combining C1 homologation, Lewis acid mediated epoxide–aldehyde isomerization, and electrophilic trapping. Mechanistic studies and labeling experiments suggest that an aldehyde enolate is a crucial intermediate of this process.