Bunpei Hatano

A novel redox system for the palladium(II)-catalyzed oxidation based on redox of polyanilines

Abstract A complex system consisting of palladium(II) acetate and polyaniline derivatives permitted the catalytic Wacker oxidation, indicating that polyanilines serve as a ligand with reversible redox capability under oxygen atmosphere. Substitution on the phenyl ring and protonic acid doping of polyanilines were found to affect the catalytic activity.

Disproportionation of diarylmethanol derivatives by using supercritical water

Non-catalytic disproportionation of diarylmethanol derivatives was found to proceed efficiently in supercritical water. This method was also applied to various diarylmethylamine derivatives to give the disproportionation products in good yields.

Cp2TiCl2-Catalyzed pinacol-type coupling of aliphatic aldehydes by use of zinc and chlorosilane

Abstract Bis(cyclopentadienyl)titanium dichloride (Cp 2 TiCl 2 ) exhibits excellent catalytic activity toward the pinacol-type coupling reaction of aliphatic aldehydes with the assistance of zinc powder and chlorosilane.

Effect of diaminotoluene on the decomposition of polyurethane foam waste in superheated water

Post-use polyurethane (PU) foam was degraded in superheated water at 423 to 623 K. The yield of diaminotoluene (TDA), one of the products, reached near 90%. The hydrolysis conditions (time and temperature) were important and the perfect liquid products could be obtained under the economic conditions at 523 K for 30 min. TDA was added to the reaction to investigate the effect on the decomposition of PU foam waste. However, in our conditions, basic additives only slightly improved the yield of TDA.

TRIFLATE ION-PROMOTED ADDITION REACTIONS OF ALLYLSILANE TO QUINOLINES AND ISOQUINOLINES ACYLATED BY CHLOROFORMATE ESTERS

Abstract Reaction of allyltrimethylsilane with a variety of quinolines acylated by chloroformate esters can be promoted by a catalytic amount of a triflate ion to afford 2-allyl-1,2-dihydroquinolines in good to high yields. A similar reaction with isoquinolines afforded benzoisoquinuclidine derivatives by consumption of 2 eq of allyltrimethylsilane.

Facile addition reactions of allylsilanes to quinolines and isoquinolines activated by chloroformate ester and a catalytic amount of triflate ion

Abstract Addition reactions of allylsilanes to quinolines acylated by chloroformate esters are promoted by a catalytic amount of triflate ion to give 2-allyl-1,2-dihydroquinoline derivatives in good yields. A variety of functional groups on quinoline ring are tolerated in the reaction. The similar reactions of allylsilanes with isoquinolines afford cyclized benzoisoquinuclidine derivatives in good yields, along with 1-allyl-1,2-dihydroisoquinoline derivatives, depending on the reaction conditions. In addition, 2-substituted allylic silanes can be utilized in the present addition reactions to afford the 2-substituted and 1-substituted 1,2-dihydro-quinolines and -isoquinolines, respectively.

Novel direct reduction of diaryl ketones to diarylmethanes using supercritical 2-propanol

We found that diaryl ketones reduce directly to diaryl alkanes under supercritical 2-propanol. This method was applied to one-pot synthesis of anthracene from anthraquinone derivatives by the addition of sulfur in excellent yields.

Zinc-Mediated Allylation and Alkylation of Aminals in the Presence of TMSCl and Diisopropylamine

An alkylation of aminals with organozinc reagents derived from allyl bromide, benzyl bromide, alpha-bromoacetate, and alpha-bromonitrile proceeded efficiently in the presence of TMSCl and diisopropylamine. This reaction system was applied to the synthesis of an antispasmodic: butaverine.

Facile synthesis of 3-methoxycarbonyl-2,2,5,5-tetra-methylpyrrolidine-1-oxyl and derivatives

We have achieved an efficient alternative synthesis of blood-brain-barrier permeable nitroxyl radicals 3-methoxycarbonyl-2,2,5,5-tetra-methylpyrrolidine-1-oxyl (1a) and 3-ethoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (1b), which affords 1a and 1b in 65% isolated yields by four steps from 2,2,6.6-tetramethyl-4-piperidone (2), respectively. This protocol is applicable to the synthesis of 3-isopropoxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (1c) and 3-carbonyl-2,2,5,5-tetramethylpyrro-lidine-1-oxyl (6).

Role of Cys73 in the thermostability of farnesyl diphosphate synthase from Geobacillus stearothermophilus

Farnesyl diphosphate synthase (FPPase) is an enzyme that catalyzes the condensation between one molecule of dimethylallyl diphosphate (DMAPP) and two molecules of isopentenyl diphosphate (IPP) to produce farnesyl diphosphate (FPP). FPP is an important precursor in the isoprenoid synthesis pathway. In this study, the crystal structure of FPPase from Geobacillus stearothermophilus (GsFPPase) was determined at 2.31 Å resolution. The structure of GsFPPase shows a three-layered all α-helical fold and conserved functional domains similar to other prenyltransferases. We have analyzed the structural features of GsFPPase related to thermostability and compared it with those of human and avian mesophilic FPPases. “Semi-conserved” regions which appear to be possible features contributing to the thermostability of FPPase were found.