Stereoselective Synthesis of 5-Substituted 2-Allyl-3-oxotetrahydrofuran-2-carboxylates Using Rhodium(II)-Catalyzed Oxonium Ylide Formation–[2,3] Shift

Application of a Stereoselective Rhodium(II)-Catalyzed Oxonium Ylide Formation–[2,3]-Sigmatropic Rearrangement of an α-Diazo-β-keto Ester to the Synthesis of 2-epi-Cinatrin C1 Dimethyl Ester

“…The stereoselective construction of substituted γ-lactones with three continuous stereocenters is one of the most important issues for the synthesis of these attractive bioactive compounds. 5 Here we report the stereoselective rhodium(II)-catalyzed oxonium ylide formation- [2,3]-sigmatropic rearrangement of α-diazo-β-keto ester 4 derived from D-glucose and its application to the synthesis of 2-epi-cinatrin C 1 dimethyl ester 2.…”

“…When the resulting ylide has an allylic substituent at the proper position, a subsequent [2,3]sigmatropic rearrangement takes place. Such metal-catalyzed carbenoid reactions have become a powerful tool for the synthesis of functionalized cyclic compounds including oxacycles.…”

“…Such metal-catalyzed carbenoid reactions have become a powerful tool for the synthesis of functionalized cyclic compounds including oxacycles. 1 We recently reported a stereoselective copper-catalyzed oxonium ylide formation- [2,3]-sigmatropic rearrangement reaction of an α-diazo ketone to give 2,6-trans-dihydropyran-3-one 2 and a rhodium(II)-catalyzed reaction of α-diazo-β-keto esters leading to 3-oxotetrahydrofurans. 3 A family of cinatrins, which were isolated from the fermentation broth of the microorganism Circinotrichum falcatisporum RF-641 by Itazaki and co-workers, possess phospholipase A 2 inhibitory activity.…”

“…1 We recently reported a stereoselective copper-catalyzed oxonium ylide formation- [2,3]-sigmatropic rearrangement reaction of an α-diazo ketone to give 2,6-trans-dihydropyran-3-one 2 and a rhodium(II)-catalyzed reaction of α-diazo-β-keto esters leading to 3-oxotetrahydrofurans. 3 A family of cinatrins, which were isolated from the fermentation broth of the microorganism Circinotrichum falcatisporum RF-641 by Itazaki and co-workers, possess phospholipase A 2 inhibitory activity. 4 Among them, the cinatrins A and B have a unique spirolactone skeleton as a key structural component, whereas cinatrin C 1 (1) contains a highly substituted γ-lactone framework that appears to be a ring-opened derivative of cinatrin B ( Figure 1).…”

“…Cinatrins are generated from a key intermediate, a substituted tetrahydrofuran-3-one 3, by (a) oxidation to a lactone, (b) introduction of the C1 unit, and (c) extension of the side chain. Furanone 3 is stereoselectively synthesized from α-diazo-β-keto ester 4 by using the rhodium(II)-catalyzed oxonium ylide formation- [2,3]sigmatropic rearrangement. The diazoketo ester 4 is easily prepared from D-glucose.…”