Hirofumi Tohma

Efficient oxidative biaryl coupling reaction of phenol ether derivatives using hypervalent iodine(III) reagents

Abstract Oxidative biaryl coupling reaction of phenol ether derivatives with the hypervalent iodine reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA), in the presence of BF3·Et2O gave a variety of substituted biphenyl and binaphthyl compounds in high yields. Replacement of PIFA with a more practical polymer-supported hypervalent iodine reagent has also been achieved.

Novel and efficient synthesis of p-quinones in water via oxidative demethylation of phenol ethers using hypervalent iodine(III) reagents

A new method for preparing p-quinone derivatives from phenol ether derivatives in water using the hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA) was developed. The present reaction proceeds in good to excellent yields under mild reaction conditions. This oxidation is expected to be environmentally benign since it uses recyclable poly-bis(trifluoroacetoxyiodo)styrene (PBTIS) in water.

A novel and useful oxidative intramolecular coupling reaction of phenol ether derivatives on treatment with a combination of hypervalent iodine(III) reagent and heteropoly acid.

The oxidative intramolecular coupling reaction of phenol ether derivatives (nonphenolic derivatives) on treatment with a novel combination of a hypervalent iodine(III) reagent, phenyliodine bis(trifluoroacetate) (PIFA), and heteropoly acid (HPA) was studied. Biaryl compounds were obtained in excellent yields on treatment of highly substituted phenol ethers. On the other hand, spirodienones were specifically formed when one of the preferred arylic coupling sites was substituted with a methoxy group in the para position.

Facile and Clean Oxidation of Alcohols in Water Using Hypervalent Iodine(III) Reagents

The facile and efficient oxidation of various alcohols such as benzylic alcohols, primary alcohols, secondary alcohols, and diols in water using the hypervalent iodine(III) reagent, iodosobenzene (PhI=O), with KBr is described. Electrospray ionization (ESI) mass spectrometric studies on the behavior of PhI=O-KBr in aqueous solution suggested that these reactions are induced by the formation of highly reactive iodine species [PhI(Br)nO –]. Further development to recyclable polymer-supported iodine(III) reagent extends the utility of this reaction to afford an environmentally benign method.

A synthetic approach to discorhabdin alkaloids: Hypervalent iodine oxidation of p-substituted phenol derivatives to azacarbocyclic spirodienones

Abstract Hypervalent iodine oxidation of O -silylated p -substituted phenols by phenyliodosyl bis (trifluoroacetate) (PIFA) in 2,2,2-trifluoroethanol gave azacarbocyclic spirodienones inn good yields.

Hypervalent iodine(III) oxidation catalyzed by quaternary ammonium salt in micellar systems

Abstract Catalytic activation of iodosobenzene (PhIO) by cetyltrimethylammonium bromide (CTAB) allows sulfide oxidation reaction to occur in high yields under mild conditions in a variety of solvents. This PhIO activation may be due to the formation of micellar or reversed micellar systems.

Synthetic Applications (Total Synthesis and Natural Product Synthesis)

Recently, hypervalent iodine reagents have been used extensively in organic synthesis. In particular, (diacyloxyiodo)benzenes such as phenyliodine(III) diacetate (PIDA) and phenyliodine(III) bis(trifluoroacetate) (PIFA) have received a great deal of attention due to low toxicity, ready availability, easy handling, and reactivities similar to that of heavy metal reagents and anodic oxidation. A variety of available reactions for natural product syntheses have been developed using PIDA, PIFA, and other iodine(III or V) reagents. These reactions are expected to be utilized for pharmaceutical and agrochemical process due to their safety, mild reaction conditions and high yields. This review focuses on recent progress in the use of hypervalent iodine reagents toward total syntheses of various biologically active natural products involving quinones, alkaloids, flavonoids, sugars, and other antibiotics.

Novel and efficient oxidative biaryl coupling reaction of alkylarenes using a hypervalent iodine(III) reagent

Abstract First facile and efficient oxidative coupling reaction of alkylarenes leading to alkylbiaryls using a combination of hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA), and BF 3 ·Et 2 O has been developed.

Hypervalent iodine(III) induced intramolecular cyclization of substituted phenol ethers bearing an alkyl azido sidechain–a novel synthesis of quinone imine ketals

A novel and efficient synthesis of quinone imine ketals from substituted phenol ethers bearing an alkyl azido sidechain using a hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate)(PIFA), is described.

A general formation of quinone imines and quinone imine acetals : an efficient synthesis of 5-oxygenated indoles

A general and high-yield synthesis of benzoquinone imines and benzoquinone imine monoacetals leading to 5-oxygenated indoles was developed