A variety of substituted cyclopropanone acetals were prepared by the addition of an organozinc reagent or a Grignard reagent to a substituted cyclopropenone acetal. MnO2- or PbO2-mediated oxidative ringopening reaction of the substituted cyclopropanone acetals affords β-alkoxyesters and protected β-aminoesters with high efficiency.
General synthesis of cyclopropenones and their acetals
作者:Masahiko Isaka、Satoshi Ejiri、Eiichi Nakamura
DOI:10.1016/s0040-4020(01)88873-6
日期:——
Metalated cyclopropenone acetals 5 react with a variety of electrophiles, including alkyl halides, carbonylcompounds, vinyl iodides, vinyl triflates, and aryl iodides, to give substituted cyclopropenone acetals in high yield. Hydrolysis of the acetal under acidic conditions gives the corresponding cyclopropenone. The reaction sequence has realized an efficient synthesis of an antibiotic penitricin
Thermal reactions of substituted cyclopropenone acetals. Regio- and stereochemistry of vinylcarbene formation and low-temperature [3 + 2] cycloaddition
of diverse electronic character have been synthesized and examined for their thermal behavior toward water and electron-deficient olefins. The substituted cyclopropenes underwent regio- and stereoselective hydration to give acrylate derivatives via vinylcarbene species, providing new data on the regio- and stereochemistry of vinylcarbene species. The also underwent regioselective [3+2] cycloadditions
Hydrostannation of Cyclopropene. Strain-Driven Radical Addition Reaction
作者:Shigeru Yamago、Satoshi Ejiri、Eiichi Nakamura
DOI:10.1246/cl.1994.1889
日期:1994.10
cyclopropenone acetals with trialkyltinhydride takes place smoothly under radical conditions to afford a variety of 2-alkyl-3-stannylcyclopropanone acetals in high yield. Comparison of the cyclopropene with acetylenes with the aid of inter- and intramolecular competitive experiments revealed the kinetically controlled nature of the reaction of the cyclopropene reaction.
Intramolecular [1 + 2] and [3 + 2] Cycloaddition Reactions of Cyclopropenone Ketals
作者:Paresma R. Patel、Dale L. Boger
DOI:10.1021/ja103933n
日期:2010.6.30
intramolecular thermalreactions of cyclopropenone ketals are reported and the work examined substrates tethered to an electron-deficient olefin bearing a single electron-withdrawing substituent. Whereas the intermolecular variants of the reactions provide only the products of an endo-selective [1 + 2] cycloaddition or a carbonyl addition reaction of a thermally generated pi-delocalized singlet vinylcarbene