Kunio Sugiyama

Photochemistry of o-methyl-substituted aromatic ketone with 5-isobutylidene-1,3-dioxane-4-,6-dione derivatives

Abstract Photolyses of o -methylacetophenone or o -methylbenzophenone with 5-isobutylidene-1,3-dioxane-4,6-diones produced novel adducts, bonding between the β-carbon of the acylales and the o -methyl carbon of the aromatic ketones.

Allenyl(vinyl)methane photochemistry. Photochemistry of γ-(3-methyl-1-phenyl-1,2-butadienyl)-substituted α,β-unsaturated ester and nitrile derivatives

Abstract The direct photolyses of the γ-(3-methyl-1-phenyl-1,2-butadienyl)-substituted α,β-unsaturated esters and nitriles gave the bicyclo[2.1.0]pentanes, cross-conjugated trienes, and several intramolecular products, while the triplet-sensitization led to the former two compounds. It was found that the photochemoselectivity depended on the substituents on the vinyl group and would be controlled by the energy using the triplet sensitizers.

Photochemistry of g-Allenyl-substituted Conjugated Alkylidenecycloalkanones

The photolyses of the γ-allenyl-substituted conjugated alkylidenecyclo- alkanones underwent the intramolecular oxa-Diels-Alder reaction and the E-Z geometrical isomerization, and for the cyclopentanone possessing a 3-methyl-1,2-butadienyl group, the intramolecular [2+2] cycloaddition also occurred. The oxa-Diels-Alder reaction takes place via photochemi- cal process of the Z-enones

Addition reaction of photoenols from o-methyl-substituted aromatic ketones with 5-alkylidene-1,3-dioxane-4,6-dione derivatives

Photolyses of 2-methylacetophenone or 2-methylbenzophenone with isobutylidene Meldrums acid or 5-isobutylidene-1,3-dioxane-4,6-dione derivatives produced novel adducts, bonding between the β-carbon of the acylals and the 2-methyl carbon of the aromatic ketones. However, the photoenol derived from benzocyclobutenols by thermolysis did not undergo the addition reaction with the acylal. The benzocyclobutenols reacted with isobutenylketene derived by pyrolysis of isobutylidene Meldrums acid to yield corresponding benzocyclobutenyl 4-methyl-3-pentenoate derivatives

Allenyl(vinyl)methane photochemistry. Photochemistry of γ-allenyl-substituted α,β-unsaturated enone derivatives

Abstract The photolyses of the γ-allenyl-substituted alkylidenecycloalkanones underwent mainly E – Z geometric isomerization; several enones gave pyrans by the photochemical intramolecular oxa-Diels–Alder reaction and bicyclo[2.1.0]pentanes by the intramolecular [2+2] cycloaddition. The photolyses of the γ-(3-methyl-1,2-butadienyl)-substituted 3-alkylidenepenta-2,4-diones led to bicyclo[2.1.0]pentane, while the γ-(1,2-propadienyl-substituted) 3-alkylidenepenta-2,4-diones underwent intramolecular [2+2] cycloaddition and intramolecular oxa-Diels–Alder reaction.

Allenyl(vinyl)methane photochemistry. Photochemistry of 4,4,7-trimethyl-5-phenyl-2,5,6-octatrienate derivatives

Abstract The direct photolysis of the diester in the title compounds gave a cross conjugated triene, [2+2] cycloadduct, pyran, and cyclopropene. The direct photolysis of the monoester afforded a cross conjugated triene, [2+2] cycloadduct, cyclopropene, and its Z -form. The sensitized photolysis of these esters afforded the trienes and [2+2] cycloadducts, which were derived from the triplet excited state of the different chromophores.

Diels-Alder reaction of photoenol of 2-methylbenzaldehyde with 5-alkylidene-1,3-dioxane-4,6-dione derivatives

Spiro- and polyspirocyclic compounds containing the 1,2,3,4-tetrahydro-1-naphthol structure were obtained by the Diels-Alder reaction of the photoenol of 2-methylbenzaldehyde with 5-alkylidene-1,3-dioxane-4,6-dione derivatives. The cycloaddition proceeded regio- and stereoselectively. However, in the case using 5-benzylidene-2,2-dimethyl-1,3-dioxane-4,6-dione and diethyl isobutylidenemalonate, the cycloaddition failed

Epoxidation of 5-Alkylidene and 5-Benzylidene Substituted 1,3-Dioxane-4,6-dione Derivatives by Hydrogen Peroxide without Catalyst

5-Alkylidene and 5-benzylidene substituted 1,3-dioxane-4,6-dione derivatives readily reacted with hydrogen peroxide at room temperature without any catalyst to give the corresponding spiro- and polyspirocyclic compounds containing oxirane ring in good yields

Photochemical reactions of N-acylbenzoxazole-2-thiones

The photochemical reactions of N-acylbenzoxazole-2-thiones 1 are examined. Irradiation of N-acylbenzoxazole-2-thiones 1 in the presence of a variety of alkenes 2 yields 2-substituted benzoxazoles 3–20 and/or the unexpected products, iminothietanes 21–29 by intramolecular trapping of the acyl group by thiolate anion of the zwitterionic intermediate I and by the phenolate anion of the zwitterionic intermediate II, respectively, derived from the spirocyclic aminothietanes AT which are formed by regioselective [2+2] cycloaddition of the carbon–sulfur double bond of 1 to the alkene double bond.