Masaya Okano

The bovine serum albumin–2-phenylpropane-1,2-diolatodioxo-somium(VI) complex as an enantioselective catalyst for cis-hydroxylation of alkenes

The 1:1 complex between an osmate ester and bovine serum albumin was found to be effective as an enantioselective catalyst in the cis-hydroxylation of alkenes, affording diols in up to 68% e.e. and turnover of the catalyst with t-butyl hydroperoxide.

Phenylselenenyl chloride in acetonitrile-water: a highly convenient reagent for hydroxyselenation of olefins and preparation of cyclic ethers from dienes

Abstract The reaction of phenylselenenyl chloride with olefins in aqueous acetonitrile affords β-hydroxyalkyl phenyl selenides in excellent yields, providing the most convenient method for hydroxyselenation of olefins so far reported. When the reaction was applied to conjugated dienes, monohydroxyselenated products were obtained in good to excellent yields. From non-conjugated dienes, on the other hand, cyclic ethers containing two phenylseleno groups were produced in good to excellent yields, the first step of this reaction being the hydroxyselenation of one double bond.

Palladium-catalyzed allylic oxidation of olefins by t-butyl hydroperoxide and tellurium(IV) oxide

Abstract Treatment of several cyclic olefins, β-pinene, allylbenzene, and estragole with palladium(II) salt in acetic acid in the presence of t-butyl hydroperoxide and tellurium(IV) oxide afforded mainly the corresponding allylic acetates. The reaction proceeded catalytically with palladium(II) salt, t-BuOOH working as a reoxidizing agent.

Stereoselective oxidation of aromatic sulfides and sulfoxides in the binding domain of bovine serum albumin

Abstract The oxidation of aromatic sulfides with achiral oxidizing agents, e.g., sodium metaperiodate (NaIO 4 ) and hydrogen peroxide (H 2 O 2 ) in the binding domain of bovine serum albumin (BSA), furnished a strong asymmetric bias (max 81%) of the product sulfoxides in fairly high chemical yields. The kinetic resolution of racemic aromatic sulfoxides was also carried out in the chiral binding domain, and the remaining unchanged sulfoxides showed optical purities ranging over 1–33% at ca. 50% completion of oxidation. The combination of the two stereoselective oxidations above mentioned produced several optically active sulfoxides of >90% optical purity in ca. 50% chemical yield. The present method constitutes a successful biomimetic approach to achieving stereoselectivities as high as obtained by sulfur-oxidizing microorganisms.

Carbodetelluration of aryltellurium(IV) compounds: olefin arylation and aromatic coupling

Abstract Aryltellurium(IV) compounds react with olefins to give the corresponding arylated olefins in moderate to quantitative yield in the presence of a palladium(II) salt. The reaction proceeds catalytically with respect to the palladium(II) salt if a suitable oxidant, such as t-butyl hydroperoxide or copper(I) or (II) chloride, is added. In the absence of olefin the corresponding biaryls are formed in moderate yield. Transmetalation of tellurium with palladium is a key step of the reaction.

Nitration of aromatic hydrocarbons and ipso-nitrosodemetallation of arylmetal compounds in sodium nitrite–trifluoroacetic acid

Treatment of aromatic hydrocarbons with sodium nitrite in trifluoroacetic acid affords nitroarenes in high yields in sharp contrast to a report in which aromatic nitration occurred only slightly in almost the same reaction system. Nitrosodemetallation at the ipso-position occurs to give nitrosoarenes in good yields by similar treatment of various arylmetal compounds (metal = Hg, Tl, Si, Sn, Pb, or Bi), nitrodemetallation hardly occurring in this case. The former reaction proceeds through attack of NO2+, while NO+ or its carrier N2O3 is the attacking species in the latter reaction.

An improved method for olefin synthesis using pyridylseleno group as a leaving group

Abstract Alkyl pyridyl selenides are oxidized by 1.5 equiv. of 30% H 2 O 2 in the THF to give olefins in good to excellent yields. The yields are always higher than the case where alkyl phenyl selendies are used under the same conditions.

A hydrolytic enzymelike behavior or bovine serum albumin in hydrolysis of p-nitrophenyl esters

Abstract The investigation of hydrolysis of p-nitrophenyl acetate (NPA) catalyzed by bovine serum albumin (BSA) proved that the initial rate in the steady state folows a Michaelis-Menten equation. In the use of D- and L-p-nitrophenyl α-methoxyphenlacetates (D- and L-NPMAs) as an enantiomeric ester, the L-enantiomer is hydrolyzed about three times faster than the D-enantiomer, mainly due to stronger binding of the former enantiomer by BSA.

Carbon–carbon bond formation in diolefins using the new reagent ‘benzeneselenenyl iodide’

‘Benzeneselenenyl iodide’, prepared in situ by the reaction of diphenyl diselenide and iodine, is a good reagent for the formation of carbocyclic compounds from diolefins.

A novel synthesis of half-protected 1,3-dicarbonyl compounds

Abstract It has been found that the reaction of enol silyl ethers with 2-ethoxy-1,3-dithiolane proceeds smoothly in the presence of zinc chloride catalyst to afford half-protected 1,3-dicarbony1 compounds in moderately good yields.