Asymmetric synthesis of β-lactams. I. The reaction of dimethylketene silyl acetal with (S)-alkylidene(1-arylethyl)amines promoted by titanium tetrachloride

Asymmetric synthesis of β-lactams by means of the reaction of dimethylketene silyl acetal with (S)-alkylidene(1-arylethyl)amines in the presence of titanium tetrachloride was studied. The extent of the asymmetric induction was in the range of 44–78% (diastereomeric purity 72–89%) and the (S)-configuration was turned to be preferentially induced at the ⁴C position of the resulting β-lactams.     

Conformational analysis of N-aryl-N-(2-azulenyl)acetamides

Aromatic amides bearing 2-azulenyl group on the amide nitrogen were synthesized and their structures were investigated. The π-electron density of the N-aryl group was found to influence the cis-trans conformational preferences of these compounds in solution. X-ray crystallography revealed that the plane of the 2-azulenyl ring has a strong tendency to lie coplanar with the amide plane when the azulene group is located on the same side as the amide oxygen atom.     

Synthesis of maremycins A and D1 via cycloaddition of a nitrone with (E)-3-ethylidene-1-methylindolin-2-one

A concise synthesis of maremycins A and D1 has been accomplished via cycloaddition of a chiral cyclic nitrone with ( E)-3-ethylidene-1-methylindolin-2-one as a key step. This synthesis clarifies the stereochemistry of the maremycins and is suitable for large-scale synthesis for biological screening.     

A novel construction of dibenzofuran-1,4-diones by oxidative cyclization of quinone-arenols

A novel oxidative cyclization of quinone-arenols 5 leading to products 6 with a dibenzofuran-1,4-dione structure, which forms the core of several natural products, has been developed and applied to the synthesis of violet-quinone (4).     

A Simple Derivation of Josephson's Formulae in Superconductivity

A simple and general derivation of Josephson's formulae for the tunneling currents is presented on the basis of Sewell's general formulation of superconductivity in relation to off-diagonal long-range order (ODLRO).