Chitaru Hirosawa

Hydrogenation of amides by the use of bimetallic catalysts consisting of group 8 to 10, and group 6 or 7 metals

Abstract Hydrogenation of amides can be catalyzed by bimetallic systems. which consist of Group 8 to 10 late transition-metals and Group 6 or 7 early transition-metals. under the mild conditions to afford the corresponding amines selectively in good to excellent yields.

Selective synthesis of heterocyclic compounds through the intramolecular substitution of phenylselenonyl group by nitrogen or carbonyl oxygen in amides

Abstract Nitrogen heterocycles were produced by the oxidation of N-[ω-(phenylseleno)alkyl]-p-toluenesulfonamides through the intromolecular substitution of the resultant phenylselenonyl group by the nitrogen atom. By the oxidation of the corresponding benzamides, on the other hand, cyclization by nitrogen or carbonyl oxygen proceeded depending on the number of carbon atoms between the nucleophile (amide) and the leaving group (selenonyl group).

Modification and limitations of the Livinghouse catalytic Pauson-Khand reaction

Abstract The difficult and impractical purification of Co 2 (CO) 8 is not necessary in the catalytic thermal Pauson-Khand reaction previously described by Livinghouse.

Cobalt-catalyzed homocoupling of terminal alkynes: synthesis of 1,3-diynes

Abstract Homocoupling of terminal alkynes proceeds using Co 2 (CO) 8 pretreated with phenanthroline to give good yields of 1,3-diynes under mild conditions.

Retention of configuration in the ritter-type substitution reaction of chiral β-arylthio alcohols through the anchimeric assistance of the arylthio group

Abstract In chiral alcohols bearing a phenylthio group at the β carbon atom. the hydroxy group is replaced by nitriles through the anchimeric assistance of the phenylthio group to afford chiral amides with retention of configuration. This stereospecific Ritter-type reaction has been utilized in the conversion of chiral glycidol derivatives to chiral cyclic imino ethers such as oxazolines bearing an arylthio group.

Catalyst precursors for the catalytic Pauson-Khand reaction

Dicobalt hexacarbonyl complexes of enynes serve as Co2(CO)8 surrogates for the intramolecular Pauson-Khand cycloaddition. Enynes with polar functional groups allow for easy separation of the catalyst cyclopentenone by-product (acid or base wash, silica gel plug column) from the desired cyclopentenone.

Enantioselectivity in the ritter-type substitution reaction via qpisulfonium ion: Retention of configuration

Abstract Ritter-type substitution reaction of optically active β-hydroxyalkyl phenyl sulfides was found to proceed with retention fo configuration through the participation of phenylthio group to afford optically active amides.

Synthesis, structure, and reduction of the cyclooctatetraene tetra-annelated with bicyclo[2.2.2]octene frameworks

Abstract The COT derivative 3 having rigid σ-frameworks has been newly synthesized and its X-ray structure determined; 3 is readily reduced to the dianion 32- in spite of severe steric hindrance.

STEREOSPECIFIC TRANSFORMATIONS OF CHIRAL COMPOUNDS USING ANCHIMERIC ASSISTANCE OF ARYLTHIO AND ARYLSELENO GROUP

A new chiral pool method is developed starting from readily available chiral oxiranes, the key step being the substitution reaction through the anchimeric assistance of the arylthio and arylseleno group. The overall transformation is the introduction of nucleopiles into the chiral carbon of the oxiranes with retention of the configuration.

Preparation of chiral aziridines from chiral oxiranes with retention of configuration

Chiral oxiranes are converted into chiral aziridines viaβ-hydroxyalkly aryl sulfides and then β-tosylaminoalkyl aryl sulfides without loss of optical purity and with overall retention of configuration.