Takashi Tsuno

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

PPh3 Propeller Diastereomers: Bonding Motif PhPPh3 Face-On π-Ar in Half-Sandwich Compounds [(π-Ar)LL′MPPh3]

Chiral-at-metal compounds (RRu,SC)/(SRu,SC)-[CyRu(1O-2N)PPh3]PF6 and (RRu,SC)/(SRu,SC)-[CyRu(2O-1N)PPh3]PF6 were prepared using anions 1O-2N– and 2O-1N– of the Schiff bases, derived from the hydroxynaphthaldehydes and (S)-1-phenylethylamine. The pure (RRu,SC)-diastereomers were obtained by crystallization. In the unit cell of (RRu,SC)-[CyRu(1O-2N)PPh3]PF6, there are three independent molecules, which differ in the propeller sense of the PPh3 ligand. Molecules [1] and [2] have (MPPh3)-configuration and molecule [3] has (PPPh3)-PPh3 configuration. PPh3 diastereoisomerism is discussed including other pairs of compounds, differing only in the PPh3 configuration. A conformational analysis reveals an internal stabilization inside the PPh3 ligand by a system of attractive CH/π interactions and a new bonding motif PhPPh3 face-on π-Ar, both characteristic features of [(π-Ar)LL′MPPh3] compounds. The propeller diastereomers interconvert via a low-energy pathway and a high-energy pathway, corroborated by density functional theory calculations.

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

Chirality in distorted square planar Pd(O,N)2 compounds.

Salicylidenimine palladium(II) complexes trans-Pd(O,N)2 adopt step and bowl arrangements. A stereochemical analysis subdivides 52 compounds into 41 step and 11 bowl types. Step complexes with chiral N-substituents and all the bowl complexes induce chiral distortions in the square planar system, resulting in Δ/Λ configuration of the Pd(O,N)2 unit. In complexes with enantiomerically pure N-substituents ligand chirality entails a specific square chirality and only one diastereomer assembles in the lattice. Dimeric Pd(O,N)2 complexes with bridging N-substituents in trans-arrangement are inherently chiral. For dimers different chirality patterns for the Pd(O,N)2 square are observed. The crystals contain racemates of enantiomers. In complex two independent molecules form a tight pair. The (RC) configuration of the ligand induces the same Δ chirality in the Pd(O,N)2 units of both molecules with varying square chirality due to the different crystallographic location of the independent molecules. In complexes and atrop isomerism induces specific configurations in the Pd(O,N)2 bowl systems. The square chirality is largest for complex [(Diop)Rh(PPh3 )Cl)], a catalyst for enantioselective hydrogenation. In the lattice of two diastereomers with the same (RC ,RC) configuration in the ligand Diop but opposite Δ and Λ square configurations co-crystallize, a rare phenomenon in stereochemistry.