Mitsunori Honda

Diastereoselective aldol condensation of acylsilane silyl enol ethers with acetals

Abstract Treatment of E - or Z -acylsilane silyl enol ethers derived from acylsilanes having an enolizable methylene proton with a mixture of aromatic aldehyde dimethyl acetals and TiCl 4 in dichloromethane gives the corresponding 2,3- anti -3-methoxyacylsilanes in high d.e., independent of the geometry of double bond in acylsilane silyl enol ethers. On the other hand, E -acylsilane silyl enol ethers react with acetals of aliphatic aldehydes to afford the corresponding aldol adducts with syn -selectivity, while the reaction of Z -isomers provides the products with anti -selectivity.

Ring-enlargement of cyclopropylacylsilanes with sulfuric or triflic acid. Selective formation of cyclobutanones or 2-silyl-4,5-dihydrofurans

Abstract Reaction of cyclopropylacylsilanes with sulfuric or triflic acid in aprotic solvent affords the corresponding cyclobutanone or 2-silyl-4,5-dihydrofuran derivatives, depending upon the substituents on the three-membered ring or acid used. The use of triflic acid results in the selective formation of the dihydrofurans.

Generation of Selenoaldehydes via Retro Diels–Alder Reaction and Their Behavior in the Reaction with Some Enophiles

Abstract The [4, 2] cycloadducts of selenoaldehydes and anthracene regenerate selenoaldehydes in situ quantitatively under neutral conditions via thermal retro Diels–Alder reaction. The reactions of selenoaldehydes generated by this method with 2-silyloxy-1,3-butadiene, 2-methoxyfuran, and 5-ethoxyoxazoles are described.

5-Isopropyl-5-methyl-2-sulfanylidene­imidazolidin-4-one

In the title compound, C7H12N2OS, the 2-sulfanylideneimidazolidin-4-one moiety is nearly planar, with a maximum deviation of 0.054 (2) Å. In the crystal, a pair of N—H⋯O hydrogen bonds and a pair of N—H⋯S hydrogen bonds each form a centrosymmetric ring with an R 2 2(8) graph-set motif. The enantiomeric R and S molecules are alternately linked into a tape along [1-10] via these pairs of hydrogen bonds.

Aggregation Behavior and Thiol-Thioester Exchange for Cationic Surfactants with Propylthioacetate Side Chain

A series of cationic surfactants containing the thioacetate group, [CnH2n+1N(CH3)2(CH2)3SCOCH3] Cl (Cn3SAc, n = 12, 14, 16), were prepared and their properties in aqueous solution were investigated by conductivity, fluorescence, and dynamic light scattering measurements. The critical micelle concentrations (CMCs) of Cn3SAc decreased to about half the value of the corresponding alkyltrimethylammonium chloride. Thioacetate was eliminated with the addition of dithiothreitol (DTT) as well as NaOH. HPLC (high performance liquid chromatography) analysis and NMR (nuclear magnetic resonance) spectroscopy showed that thiol surfactants, [CnH2n+1N(CH3)2(CH2)3SH]Cl (Cn3SH), were generated upon the addition of DTT in aqueous solution via thiol-thioester exchange, whereas gemini surfactants, [CnH2n+1N(CH3)2(CH2)3SS(CH2)3N(CH3)2CnH2n+1]2Cl (2Cn3SS), were generated upon incubation in alkaline solution via hydrolysis and air oxidation.

1-Acetyl-5-(4-fluoro-phen-yl)-2-sulfanyl-ideneimidazolidin-4-one.

In the title compound, C11H9FN2O2S, the 2-sulfanylideneimidazolidin-4-one moiety is essentially planar, with a maximum deviation of 0.0183 (14) Å. The mean plane of this moiety is approximately coplanar with the attached acetyl group and perpendicular to the benzene ring, making dihedral angles of 9.70 (14) and 86.70 (6)°, respectively. In the crystal, molecules are linked by N—H⋯O hydrogen bonds between the amide NH and acetyl C=O groups, forming a C(6) chain along the a-axis direction.