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Photocleavage of the N–O bond of N-(9-anthroyloxy)-9-fluorenylideneamine and its 1-and 2-anthroyloxy derivatives takes place efficiently in acetonitrile in the excited singlet state attributed to the fluorenylidene moiety. This made it possible for the first time to directly observe anthroyloxyl radicals by the transient absorption method. The quantum efficiency for photocleavage decreases remarkably in benzene, in which the lowest excited singlet state is attributed to the anthroate moiety. All the three kinds of anthroyloxyl radicals are much less reactive in decarboxylation, addition to olefins, and hydrogen-atom abstraction than benzoyloxyl and 1- and 2-naphthoyloxyl radicals; 9-anthroyloxyl radicals supposedly undergo intramolecular addition–elimination in the ipso-position in equilibrium with α-lactonic spirodihydroanthryl radicals, as indicated by one-color and two-color laser photolyses.

A competitive transannular reaction occurred to give 7-methyltricyclo[3.3.1.03,7]nonan-3-ol (5) and 1-adamantanol (6) in the non-mediated electroreduction of 7-methylenebicyclo[3.3.1]nonan-3-one (1) in N,N-dimethylformamide. The apparent temperature dependence of the regioselectivity of the reaction may be attributed to the competitive operation of both kinetic and thermodynamic controls in the cyclization of the ketyl radical anion. The differences in the parameter of activation between the 5-exo- and 6-endocyclizations of 1•-, ΔΔH‡(5-exo - 6-endo) and ΔΔS‡(5-exo - 6-endo), were evaluated to be -3.1 kcal mol-1 and -11 cal mol-1 K-1, respectively. Semiempirical PM3 (RHF and UHF) calculations were also carried out to elucidate the reaction mechanism.

A significant directive effect of the 2-axial hydroxy group appeared in the LiAlH4, NaBH4, and Zn(BH4)2 reduction of cyclohexanone, while the 3-axial hydroxy group exhibited a steric hindrance. The distance between the carbonyl carbon and the hydroxy group which interacts with the hydride reagent is mainly responsible for such a difference. In the reduction of Na[B(OAc)3H], both the 2- and 3-axial hydroxycyclohexanones exclusively gave the products which were obtained by the hydride approaching from the side of the hydroxy group. The key point of this stereoselectivity is the formation of Na[B(OAc)2(OR)H], which is far more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide.

The complex metal hydride reductions of 2-t-butyl-1,3-dioxan-5-one (1) and 3-oxoquinolizidine (3) are faster than those of the corresponding carbocyclic compounds, 4-t-butylcyclohexanone (2) and trans-2-decalone (4). The stereoselectivities were similar in the LiAlH4 reduction, but the heteracyclohexanones exhibited higher stereoselectivity with NaBH4. These facts are discussed in terms of the intramolecular orbital interaction.

In order to get insight into the effect of the different fixations of the conjugated systems of the aminochalcone-dyes on both the photophysical behavior and the quenching scheme of photoinitiation systems in a film, photophysical behavior of 2-benzoyl-6-(dimethylamino)benzo[b]furan (A) on 355 nm excitation with or without a radical-generating reagent, 2,4,6-tris(trichloromethyl)-1,3,5-triazine (TRI), in poly(methyl methacrylate) (PMMA) film has been investigated by laser flash photolysis using a total reflection cell. Dye A showed characteristic dual fluorescences of which the lifetimes, τSs, of shorter- and longer-wavelength components were evaluated to be 3.2 and 5.4 ns, respectively. The fluorescences were quenched by TRI with different static quenching distances, (Rs)Ss, of 1.3 and 1.5 nm for Ashort and Along, respectively. The static quenching distance of the initial triplet absorption of A, (Rs)T, was evaluated to be 1.5 nm. In addition, deconvolution analysis of the lifetimes of fluorescent dyes h...

The 2- and 3-axially substituted methoxy groups in cyclohexanones exhibit steric hindrance similar to that of the methyl group in LiAlH4 and NaBH4 reductions. The chelate complex formation between the zinc ion and the two oxygens in the molecule was suggested in the zinc borohydride reduction. The relative reactivities of cyclohexanones in which the 2-axial position is substituted by the methyl or the methoxy group in the LiAlH4 reduction strongly support Cieplak’s proposal, which focuses on the importance of the stabilization of the transition state by anti-periplanar allylic bonds.

Intramolecular quenching of the excited singlet state of a phenanthrene moiety was more efficient in (E)-2-(p-methoxyphenyl)-2-butenyl 9-phenanthrenecarboxylate (E-ABP) than in its Z isomer (Z-ABP) in benzene. The quenching is proposed to proceed in a through-space fashion on the basis of efficiencies of isomerization and photophysical processes as well as molecular orbital calculations.

The electrocatalytic hydrogenation of the title compound was examined over Raney Ni, Raney Co, Pt-carbon and Pd-carbon as hydrogen-active powder electrodes. A high conversion of ketone to alcohol was observed on the Raney catalysts when the pKa values of the proton sources employed were around 5. The metal-on-carbon catalysts showed a relatively low conversion of ketone regardless of the proton sources. The stereochemistry of the reaction was examined.

Irradiation of (E)-3-(p-methoxyphenyl)-3-pentenyl, (E)-4-(p-methoxyphenyl)-4-hexenyl, and (E)-5-(p-methoxyphenyl)-5-heptenyl 9-phenanthrenecarboxylates (B-2E, B-3E, and B-4E, respectively) in benzene gave intramolecular [2+2] cycloadducts, cyclobutane derivatives (CB-2, CB-3, and CB-4, respectively) possessing the same conformation as an intermolecular [2+2] cycloadduct (CB-0) between methyl 9-phenanthrenecarboxylate (9-MCP) and trans-anethole (t-AN), and oxetane derivatives (OX-2, OX-3, and OX-4, respectively) arising from intramolecular cycloaddition between the carbonyl group and the olefinic double bond. However, (E)-4-(p-methoxyphenyl)-3-butenyl and (E)-5-(p-methoxyphenyl)-4-pentenyl 9-phenanthrenecarboxylates (A-2E and A-3E, respectively) afforded only products derived from oxetane precursors.

The efficiency of [2+2] photocycloadduct formation was examined by measuring fluorescence lifetimes and the quantum yields of fluorescence and product formation in two series of p-methoxyphenylalkenyl 9-phenanthrenecarboxylates (A-nE and B-nE). In (E)-3-(p-methoxyphenyl)-3-pentenyl, (E)-4-(p-methoxyphenyl)-4-hexenyl, and (E)-5-(p-methoxyphenyl)-5-heptenyl 9-phenanthrenecarboxylates (B-2E, B-3E, and B-4E, respectively) the intramolecular quenching leads to product (cyclobutane+oxetane) formation in almost unit efficiency, while in (E)-4-(p-methoxyphenyl)-3-butenyl and (E)-5-(p-methoxyphenyl)-4-pentenyl 9-phenanthrenecarboxylates (A-2E and A-3E, respectively) exciplex→product efficiency is a half to three quarters. Intermediacy of plural exciplex intermediates is suggested in the present bichromophoric systems on the basis of exciplex quenching results.