Converting gem-dimethyl groups into cyclopropanes via Pd-catalyzed sequential C-H activation and radical cyclization

A novel route to the synthesis of cyclopropane derivatives is described. 1,1-Dimethyls in 2-(1,1-dimethylalkyl)dimethyloxazolines are first converted into 1,3-diiodide derivatives via Pd-catalyzed sequential C-H activation and then radically cyclized to provide 2-(1-alkylcylclopropyl)dimethyloxazolines. The use of EtOAc as a solvent is crucial for the diiodination of the functionalized substrates. [reaction: see text]     

Sigma-chelation-directed C-H functionalizations using Pd(II) and Cu(II) catalysts: regioselectivity, stereoselectivity and catalytic turnover

Recent progress in sigma-chelation directed C-H functionalization from the authors' group is described to illustrate the challenges and opportunities in the development of synthetically-useful catalytic reactions involving C-H activation as the key step. Emphasis is placed on strategies for developing catalysis under mild conditions and controlling regio- and stereoselectivity.     

Synthesis of derivatives of 4,5-dihydrofuran,furan, and hexahydrobenzofuran from conjugated alkenynes

The regiochemistry of the reaction of 1,2- and 1-substituted derivatives of 1-buten-3-yne and its 4- and 2,4-substituted derivatives of the isoprenoid type with acetoacetic ester and acetylacetone in the presence of the manganese(III) acetate-copper(II) acetate oxidative system was studied. Derivatives of 4,5-dihydrofuran, furan, and hexahydrobenzofuran were obtained.Communication 137 from the series Reactions of unsaturated compounds. See [1] for communication 136.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 24, No. 3, pp. 317–323, March, 1988.     

Concise syntheses of (+)- and (−)-methylenolactocins and phaseolinic acids

(+)- and (−)-Methylenolactocins and phaseolinic acids are synthesized in four steps via asymmetric syn- and anti-aldol reactions of chiral N-succinyl-2-oxazolidinones using the same set of reagents.     

Absence of first-order transitions in a chainlike metamagnet

A model system consisting of ferromagnetic Ising chains coupled antiferromagnetically to neighboring chains is studied by regarding each chain as lying in a molecular field produced by its neighbors. Analytical and numerical results indicate that the phase transition in a magnetic field at low temperatures is second-order.