非共平面的に芳香環が集積した分子群に関する特異な反応挙動の解析とその空間構造の特徴解明

抄録

The polyaromatic ketone compounds having non-coplanarly aromatic-ring-accumulated structure have been studied from the viewpoint of uniqueness and specificity in reaction behavior and characteristics in spatial organization. Synthesis of 1-aroylated and 1,8-diaroylated derivatives of 2,7-dimethoxynaphthalene was successfully performed by the action of arenecarboxylic acids or their chlorides with the aid of adequate acidic mediator: Lewis/Brønsted acid or direct condensation reagent. The aroylation shows distinct dependence on acidic mediator employed. The product distribution among 1-aroyl-, 1,8-diaroyl-, and 3-aroylnaphthalenes is strongly affected by the kind of acidic mediator. With the aid of the monitoring of the time-course of the product distribution, interconversion from the 1-aroylated- and 1,8-diaroylated derivatives to the 3-aroylated one is revealed. These reaction behaviors including acid-strength-dependent reversibility are well interpreted from the nature of highly congested non-coplanar geometry of the polyaromatic ketone products. By the separate reaction of the isolated aryl-aryl ketones, the acid-mediated retro-aroylation of aromatic ketone molecules is confirmed. Moreover, the aroylated 2,7-dimethoxynaphthalene homologues/analogues show susceptible ether scission of the methyl ether moiety adjacent to aroyl substituents. These unique and specific reaction behavior compared to conventional aromatic ketones and aromatic methyl ether is interpreted due to the non-coplanarly situated carbonyl group of the aroyl moieties against naphthalene ring with essentially perpendicular situation. The spatial organization of these compounds has been investigated with expectation of useful information for clarification of reactivity-structure relationship analysis and elucidation of structure determining factors. On the basis of the X-ray crystal structure analysis of about 80 homologous/analogous compounds and NMR spectroscopic study including variable temperature measurement, both the protocols of determination of single molecular and packing structures in crystal and analysis of bond rotation behavior in solution were undertaken. The structure characteristics about symmetric nature of the single molecule, stabilizing intermolecular interaction, and alignment of molecules in crystal and the rotation capability of the bonds in solution were discussed to clarify the determining factors for spatial organization and reaction behavior of the non-coplanarly aromatic-ring-accumulated compounds and to design the molecular materials having such type of spatial organization in the future.