Stereoselective Aminopalladation and Oxypalladation and Their Application to the Synthesis of Natural Products

Stereoselective aminopalladation and oxypalladation are very important approaches for the synthesis of various natural products which contain N- and O-hetero-alicycles. The author has reviewed recent progress of synthesis of natural products using Pd(II)-catalyzed aminopalladation and oxypalladation, including our work within this decade.ArticleNATURAL PRODUCT COMMUNICATIONS. 8(7):1005-1010 (2013)journal articl

Synthesis of (+)-boronolide and (+)-deacetylboronolide using Pd-catalyzed carbonylation and lactonization

(+)-Boronolide and (+)-deacetylboronolide were synthesized using Pd-catalyzed CO insertion and lactonization as the key step. As to the C-13 NMR data of (+)-deacetylboronolide, the assignment at C-6 position should be revised.ArticleTETRAHEDRON LETTERS. 55(17):2822-2824 (2014)journal articl

Synthesis of both enantiomers of akolactone B and (+)-ancepsenolide

The syntheses of (+)- and (−)-akolactone B and (+)-ancepsenolide were accomplished using a Pd-catalyzed carbonylation. As to the absolute configuration of akolactone B, making a comparison of the specific rotation of both enantiomers of synthetic akolactone B and the natural compound suggests that the absolute configuration at the 4-position of akolactone B is (R).ArticleTETRAHEDRON-ASYMMETRY. 25(20-21):1367-1371 (2014)journal articl

Synthesis of legioliulin, a fluorescent isocoumarin compound, isolated from Legionella dumoffii using cyclic acylpalladation and Heck reaction

Concise synthesis of legioliulin, an isocoumarin compound isolated from Legionella dumoffii, was achieved. Isocoumarin ring of legioliulin was constructed using cyclic acylpalladation. Chain elongation was performed using Heck reaction using t-butylphosphine as a ligand. (C) 2016 Elsevier Ltd. All rights reserved.ArticleTETRAHEDRON LETTERS.57(35):3942-3944(2016)journal articl

EFFICIENT STEREOSELECTIVE SYNTHESIS OF CATECHIN TRIMER DERIVATIVE USING SILVER LEWIS ACID-MEDIATED EQUIMOLAR CONDENSATION

A stereoselective synthesis of benzylated catechin trimer under intermolecular condensasion is achieved using equimolar amount of dimeric catechin nucleophile and monomeric catechin electrophile catalyzed by AgOTf or AgBF(4). The coupled product can be transformed into procyanidin C2 by a known procedure.ArticleHETEROCYCLES. 83(4):739-742 (2011)journal articl

Heat treatment of Chinese quince polyphenols increases rat plasma levels of protocatechuic and vanillic acids

The effect of heat-treated Chinese quince polyphenols on plasma antioxidant activity and the plasma levels of aromatic acids after oral administration to rats was investigated. The aqueous solution of Chinese quince polyphenols (CP) that had been extracted using 60% (v/v) acetone turned reddish during the heat treatment in the presence of citric acid. During the treatment, decreases in polymeric procyanidins and an increase in monomers, dimers and oligomers were observed. In the oral administration study, CP subjected to 2 h of heat treatment (CPT-2) caused a significant increase in antioxidant activity as assessed by the ferric reducing ability of plasma (FRAP) method. In addition, CP, CP + citric acid and CP subjected to 8 h of heat treatment (CPT-8) also tended to increase the FRAP value but the increase was not significant. Of the plasma aromatic acids detected, protocatechuic acid increased in all rats given the polyphenols. Vanillic acid increased significantly in rats given CPT-2 and CPT-8, reflecting a facilitatory effect of heat treatment on the intestinal absorption of protocatechuic acid and subsequent conversion by catechol-O-methyl transferase. These results suggested that the heat-induced breakdown of Chinese quince polyphenols seems to be an effective method of leading to an elevation of plasma antioxidant activity and levels of aromatic acid that are health-benefiting compounds derived from procyanidins.ArticleFOOD CHEMISTRY. 118(3):757-763 (2010)journal articl

A CONCISE SYNTHESIS OF SOLAMIN AND CIS-SOLAMIN, MONO-THF ACETOGENINS FROM ANNONA MURICATA

A concise total synthesis of solamin (1) and cis-solamin (2) was performed using an epoxy alcohol (11) as a versatile chiral building block for synthesizing the stereoisomers of the mono-THF annonaceous acetogenins.ArticleHETEROCYCLES. 78(9):2369-2376 (2009)journal articl

Asymmetric syntheses of daedalin A and quercinol and their tyrosinase inhibitory activity

Stereoselective syntheses of daedalin A and quercinol, an enantiomer of daedalin A, is described. The tyrosinase inhibitory activities of daedalin A and quercinol were examined. The activity of quercinol was weaker than that of daedalin A at high concentration.ArticleBIOORGANIC & MEDICINAL CHEMISTRY LETTERS. 20(3):1063-1064 (2010)journal articl

Selective Synthesis of Epicatechin Dimers By Zinc(II) Triflate Mediated Self-Condensation

efirst: 25 Aug 2014Epicatechin dimers were synthesized by zinc(II) triflate mediated self-condensation reactions of epicatechin monomer derivatives. One synthesized dimer was successfully converted into procyanidin C1.ArticleSYNTHESIS-STUTTGART. 46(24):3351-3355(2014)journal articl

Synthesis of both enantiomers of akolactone B and (+)-ancepsenolide

The syntheses of (+)- and (−)-akolactone B and (+)-ancepsenolide were accomplished using a Pd-catalyzed carbonylation. As to the absolute configuration of akolactone B, making a comparison of the specific rotation of both enantiomers of synthetic akolactone B and the natural compound suggests that the absolute configuration at the 4-position of akolactone B is (R).ArticleTETRAHEDRON-ASYMMETRY. 25(20-21):1367-1371 (2014)journal articl