An enantioselective intramolecular oxidative cyclization of 4-alkenoic acids was developed. The reaction proceeded via a π-allyl Pd intermediate generated by an allylic C–H activation to give γ-lactone derivatives with moderate to good enantioselectivity. Spiro bis(isoxazoline) ligand, SPRIX, was indispensable for this asymmetric transformation.
Palladium(0)-Catalyzed Coupling Cyclization of Functionalized Allenes with Hypervalent Iodonium Salts
作者:Suk-Ku Kang、Tae-Gon Baik、Alexander N. Kulak
DOI:10.1055/s-1999-2613
日期:1999.3
The palladium(0)-catalyzed coupling reaction of allenic alcohols, amines, acids with hypervalent iodonium salts afforded the cyclized heterocyclic tetrahydrofurans, tetrahydropyrans, pyrrolidines, piperidines, or lactones under mild conditions.
An unusual and efficient reaction of 2-methylene-3-phenyloxetane in the presence of lithium and 4,4′-di-tert-butylbiphenyl in THF
作者:Mehrnoosh Hashemzadeh、Amy R Howell
DOI:10.1016/s0040-4039(00)00060-5
日期:2000.3
When 2-methylene-3-phenyloxetane (4) was treated with excess lithium and DTBB (cat.), lactone 6 was isolated as an unexpected product in high yield. It is postulated that 6 arises from a coupling of a radical enolate derived from 4 and the enolate of acetaldehyde, a product of THF decomposition under the reaction conditions.