Synthesis of a lactone diastereomer of the cembranolide uprolide D
James A Marshall1, Céline A Griot, Harry R Chobanian
1Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA. jam5x@virginia.edu
Abstract:
A convergent stereoselective synthesis of a C1/C14 bis-epimer of uprolide D is described in which an intramolecular Barbier-type reaction was employed for macrocyclization with concomitant introduction of the C1 and C14 stereocenters of a fused α-methylene lactone ring through an anti-Felkin-Anh transition state. Unlike previous examples of allyl chromium additions, none of the Felkin-Anh derived adduct could be detected.
Related Concept Videos
Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
Preparation of Diols and Pinacol Rearrangement
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Preparation of Epoxides
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...


