Yoshiharu Matsubara

Selective and one-pot formation of phenols by anodic oxidation☆

Abstract Direct monohydroxylation of benzene and substituted benzenes was successfully performed by anodic oxidation to form the corresponding phenol derivatives in good yields. The anodic oxidation was generally carried out in a mixed solvent of trifluoroacetic acid and dichloromethane containing triethylamine using a divided cell equipped with a platinum plate as the anode, a carbon rod as the cathode. Benzene derivatives having electron withdrawing groups were suitable for the present electrochemical oxidation. It was clarified that aryltrifluoroacetates were formed as the initial products from the reaction of the radical cations, generated by one electron transfer from the substrates, with trifluoroacetic acid, followed by hydrolysis during work-up to give the corresponding phenols.

CARBON-CARBON BOND FORMATION USING MANGANESE(III) ACETATE AS AN ELECTROCHEMICAL MEDIATOR

Abstract Anodic oxidation in a solution containing a variety of olefins and a small amount of Mn(OAc)2·4H2O brought about Mn+3-mediated carbon—carbon bond formation, such as efficient carboxymethylation of styrene derivatives to the corresponding γ-aryl-γ-butyrolactones, and selective coupling of active methylene compounds with non-activated monoolefins, unconjugated dienes or 5-arylpent-1-enes.

Regioselective azidomethoxylation of enol ethers by anodic oxidation

Abstract Anodic oxidation of enol ethers 1 in methanol containing sodium azide using a divided cell brought about facile and regioselective azidomethoxylation to give the corresponding acetals 2 of α-azido carbonyl compounds in good yields.

Isolation and characterization of new limonoid glycosides from Citrus unshiu peels.

Three limonoid glycosides were isolated from Citrus unshiu peels, and their structures were determined based on MS and NMR spectroscopic data as nomilinic acid 17-O-beta-D-glucopyranoside (1), methyl nomilinate 17-O-beta-D-glucopyranoside (2), and obacunone 17-O-beta-D-glucopyranoside (3). In particular, the location of the sugar moiety was clearly determined by the B/E constant linked scan FABMS method. No limonoid glycosides obtained here were found to have antitumor activity in NCI-H292 and EL-4 cell lines.

Bioactive glycosides in citrus fruit peels

Abstract Since 1980s we have been investigating bioactive compounds in citrus fruit peels. We have successfully isolated seventy-three glycosides including thirty-four new compounds. They were flavonoid glycosides, phenylpropanoid glycosides, terpenoid glycosides, limonoid glycosides, and alkyl glycosides. The biological activities of the compounds were studied for the utilization as hypotensive and hypertensive drugs. In this manuscript, recent works are briefly reviewed focussing on the isolation and a mutual relationship between the structures of the compounds and their biolosical activities.

Placental Na+, K+ activated ATP-ase activity in SHRSP in connection with pregnancy induced hypertension and intra-uterine growth retardation.

1. Placental Na+, K+‐ATPase activities were measured in connection with the active transport of amino acid, intrauterine growth retardation (IUGR) or small for date infants (SFD) in salt‐loaded pregnant SHRSP.

Selective cleavage of polycyclic cyclopropanes by electrochemical oxidation

Abstract Anodic oxidation in acetic acid of polycyclic cyclopropanes, namely tricyclene, cyclofenchene, and longicyclene, followed by hydrolysis brought about stereo- and regioselective formation of the corresponding homoallylic alcohols as the main product in good yields.

Unusual Rearrangement by Anodic Oxidation of Cycloalkanones in the Presence of Trifluoroacetic Acid

Anodic oxidation of cyclopentanone and cyclohexanones in a mixed solvent of CF3COOH and CH2C12 containing triethylamine led to unusual rearrangement to give selectively γ-valerolactone and a mixture of γ-and δ-lactones, respectively.

Investigation of functional molecules in African Celosia argentea L.

Abstract Five glycosides were isolated from the leaves of Celosia argentea L. and their structures were determined based on UV, MS, 1 H NMR and 13 C NMR spectroscopic data as 1-(4- O -β-glucopyranosyl-3-methoxyphenyl) propane-2-ene (citrusin C, 1 ), 3- O -β-glucopyranosyl-1 H -indole (indican, 2 ), (3 Z )-hexenyl-(1- O -α-rhamnopyranosyl-β-glucopyranoside) ( 3 ), (3 Z )-hexenyl-1- O -β-glucopyranoside ( 4 ), and (7 E )-6,9-dihydromegastigma-7-ene-3-one-9- O -[β-glucopyranoside ( 5 ). On bioassay on the germination of lettuce, compound 1 , the aglycone of 1 ( 1a ), and the aglycone of 3 (3a) exhibited growth inhibitory activity, whereas compound 2 and 3 exhibited growth promotive activity. Compounds 1 –5 were detected in the leaves of Celosia argentea L. for the first time in this study.

Hydroboration of Alkenes or Alkynes by Electrolysis of Sodium Borohydride

We have already reported that electrochemical oxidation of the solution containing sodium borohydride led to the generation of diboranes (BH3). Application of this method to reductive reactions of aliphatic carboxylic acids was successful to form the corresponding primary aliphatic alcohols selectively.1) These reactions was quite familiar to us as one of the typical transformations by use of diboranes.