Toshihide Hatsui

The methylene-blue-sensitized photoreaction of quadricyclane. Mechanism of oxidation

Abstract The methylene-blue-sensitized photo-oxidation of quadricyclane (1) gave two 5-methoxy-3-nortricyclanols, two 7-methoxy-5-norbornen-2-ols and two 5-chloro-3-nortricyclanols. Their formation is best explained by a photoelectron transfer from 1 to the excited methylene blue molecule. No involvement of singlet oxygen was confirmed. The photoisomerization of 1 to norbornadiene was also observed.

Mesomorphic properties of troponoid esters and amides with cholest‐5‐ene‐3β‐carboxylic acid moiety

Troponoid esters and amides connected with cholest‐5‐ene‐3β‐carboxylic acid have been synthesized to characterize their mesomorphic properties and to compare them with those of the corresponding benzenoids. 5‐Alkoxytroponyl esters and amides with a long alkoxy group exhibited a twist grain boundary A* phase, as well as chiral nematic and smectic A* (SmA*) phases. The corresponding benzenoid esters exhibit SmA* and blue phases and the benzenoid amides only a SmA* phase. The differences between the mesomorphic properties are discussed in terms of the structural features of the core.

Effects of a Polar Lateral Nitro Group on the Appearance of Mesophases of 4,4′-Bis(benzoyloxy)biphenyls

Four types of 4,4′-bis(benzoyloxy)biphenyls were synthesized to investigate the effects of the lateral polar nitro group on appearance of mesophases as well as improvement of the mesomorphic property. In the case of 4,4′-bis(4-alkoxybenzoyloxy)biphenyls and 4,4′-bis(3,4- and 2,4-dialkoxybenzoyloxy)biphenyls, their transition temperatures were reduced by the introduction of the polar lateral nitro group because of the increasement of the molecular breadth. The nitro group in 4,4′-bis(3,4,5-trialkoxybenzoyloxy)biphenyls enhanced the transition temperatures and mesomorphic properties since the trialkoxy derivatives without a nitro group were not mesomorphic and those with a nitro group had a hexagonal columnar phase. The introduction of the nitro group did not increase the molecular breadth of the trialkoxy derivatives because they already have the wide molecular breadth.

Single Crystal-To-Single Crystal Transformation of A Syn -Tricyclo[4.2.0.0 2,5 ]Octane to A ( Z , Z )-Cycloocta-1,5-Diene Under X-Ray Irradiation

We have observed that a syn-tricyclo[4.2.0.0 2,5 ]octane derivative (1) isomerized keeping the single crystalline state to a (Z,Z)-cycloocta-1,5-diene derivative (2) during the X-ray crystallographic analysis. In this paper, we report that an octahydro derivative (5) of 1 transformed to a (Z,Z)-cycloocta-1,5-diene derivative (6) keeping the single crystalline state. Similarly, irradiation of an acetonitrile solution of 5 with high-pressure mercury lamp (>400nm) in the presence of a sensitizer, 9,10-dicyanoanthracene, gave 6 in good yields via a radical cation mechanism.

Photoaddition of methyl 2,4-dioxopentanoate to norbornadiene and quadricyclane

Abstract The photocycloaddition of methyl 2,4-dioxopentanoate ( 1 ) to norbornadiene gave a diketo ester ( 4 ), derived from the expected [2 π +2 π ] cycloadducts, together with a [2 π +2 π +2 π ] cycloadduct ( 6 ), rearranged tricyclic ester ( 5 ), 7-substituted norbornene ( 7 ) and norbornadiene ( 8 ). The similar reaction of 1 with quadricyclane gave, 4, 5 and an oxetane ( 9 ), but no 7 . The occurrence of 5 signifies the formation of zwitter ions via an electron transfer process.

Kinetic studies of the high-pressure [6+4]π cycloaddition of tropone to cyclohexa-1,3-diene

The kinetics of the [6 + 4]π cycloaddition of tropone to cyclohexa-1,3-diene have been studied in the temperature range 80–95 °C at pressures up to 2 000 bar in isopropylbenzene, N,N-dimethylformamide, and 1,4-dioxane. Activation parameters were in the range for a typical concerted intermolecular cycloaddition, and were mutually consistent in each solvent, but inconsistent with those reported for a high-pressure kinetic analysis of tropone and cyclopentadiene by le Noble. The effect of solvation on the cycloaddition reactions of tropone should be carefully re-evaluated.

Synthesis of troponoid analogues of calix[4]arene by the reaction of dichlorocarbene with calix[4]arene

Abstract Troponoid analogues of calixarene, having a tropone or a cyclohepta[ b ]chromen-6(11 H )-one ring were synthesized by the reaction of dichlorocarbene with p - tert -butylcalix[4]arene. The cyclohepta[ b ]chromene derivative dimerized easily to give meso - and dl -dimers.