T. Matsushima

Synthetic studies of 18-membered anti-tumor macrolide, tedanolide. Computer-aided conformational design of a seco-acid derivative for efficient macrolactonization

Abstract Computer-aided conformational analyses are successfully applied to the synthesis of a key intermediary 18-membered lactone of tedanolide ( 1 ). The design of a seco-acid derivative based on computation in order to achieve its efficient macro-lactonization is described.

HOT-ATOM MECHANISM AND REACTION SITES IN PHOTOINDUCED CARBON MONOXIDE OXIDATION ON A STEPPED PLATINUM (113) SURFACE

Angular and velocity distributions of product CO2 were measured in CO oxidation photoinduced by 193 nm laser pulses of 16 ns duration on a stepped Pt(113) surface. At low oxygen and CO coverages, the CO2 desorption was collimated at ±23° from the surface normal in a plane along step edges. CO2 is formed by the collision between CO on an atop site and translationally hot oxygen atoms emitted along the axes of oxygen molecules that lie along the step edge, resulting in declined desorption due to momentum transfer from the hot atoms. With increasing oxygen coverage, new components collimating at the (111) terrace and (100) step normal became major, while an increase in the CO coverage enhanced the CO2 desorption collimated in the normal direction. It is likely that at high coverage the reaction sites extend to (111) and (100) microfacets and also to surface troughs, yielding the above three components. The translational temperature of product CO2 was often maximized at around angles where the CO2 desorption ...

Reaction sites of photo-induced carbon monoxide oxidation on a stepped platinum (113) surface

Abstract The reaction sites of CO oxidation induced by 193 nm irradiation were studied in the coadlayer of CO and O2 on Pt(113) = (s)2(111) × (001) around 110 K with the angular and velocity distributions of desorbing product CO2. At low coverages, the CO2 desorption takes place in surface troughs. On the other hand, three kinds of reaction sites are found at high O2 coverage, where three additional desorption components, peaking along the (111) terrace, the (001) step and the bulk surface normal, become predominant.

Conformational analysis of the 16-membered epoxyenone and complete stereoselection in the reduction of its C9 carbonyl group, the key reaction in the synthesis of maridonolides

Abstract 16-membered epoxyenone ( 2 ), the key synthetic intermediate of maridonolides, has two distinct conformational isomers in solution. The conformational analysis of them by virtue of NMR measurement and the profound effect of their conformations on reactivity and stereoselectivity in the reduction of the C9 carbonyl group are discussed.

Two distinct conformational isomers of the 16-membered epoxyenone, the key synthetic intermediate of maridonolides. Conformational analysis and completely stereoselective reduction of the C9 carbonyl group1)

Abstract The key synthetic intermediate of maridonolides ( 2 ) has two easily detectable conformational isomers in solution. The conformational analysis of the 16-membered epoxyenone ring and the effect of conformation on reactivity in the reduction of the C9 carbony group are described.