Mitsuru Shoji

Dry and wet prolines for asymmetric organic solvent-free aldehyde–aldehyde and aldehyde–ketone aldol reactions

Dry and wet prolines were found to catalyze the direct aldol reactions of aldehyde-aldehyde and aldehyde-ketone, respectively, to afford aldols with excellent diastereo- and enantioselectivities, and an organic solvent-free reaction was realized in some cases.

Total Synthesis of (+)‐Epoxyquinols A and B

which show anti-angiogenic activity,but have different structuralproperties from the knownangiogenesis inhibitors. To facilitate elucidation of themechanism of action of epoxyquinols A and B, the develop-ment of a method for their totalsynthesis and derivatization ishighly desirable. Though structurally epoxyquinols A and Bhave a highly functionalized and complicated heptacyclic ringsystem containing 12 stereocenters, biosynthetically it isproposed they are formed by an unusualoxidative dimeriza-tion of the much simpler epoxycyclohexenone 3(Scheme 1).

Epolactaene binds human Hsp60 Cys442 resulting in the inhibition of chaperone activity.

Epolactaene is a microbial metabolite isolated from Penicillium sp., from which we synthesized its derivative ETB (epolactaene tertiary butyl ester). In the present paper, we report on the identification of the binding proteins of epolactaene/ETB, and the results of our investigation into its inhibitory mechanism. Using biotin-labelled derivatives of epolactaene/ETB, human Hsp (heat-shock protein) 60 was identified as a binding protein of epolactaene/ETB in vitro as well as in situ. In addition, we found that Hsp60 pre-incubated with epolactaene/ETB lost its chaperone activity. The in vitro binding study showed that biotin-conjugated epolactaene/ETB covalently binds to Hsp60. In order to investigate the binding site, binding experiments with alanine mutants of Hsp60 cysteine residues were conducted. As a result, it was suggested that Cys442 is responsible for the covalent binding with biotin-conjugated epolactaene/ETB. Furthermore, the replacement of Hsp60 Cys442 with an alanine residue renders the chaperone activity resistant to ETB inhibition, while the alanine replacement of other cysteine residues do not. These results indicate that this cysteine residue is alkylated by ETB, leading to Hsp60 inactivation.

The Baylis-Hillman reaction under high pressure induced by water-freezing

Abstract High pressure (about 200 MPa), which was realized by freezing water in a sealed autoclave, has been successfully applied to the Baylis–Hillman reaction, in which an efficient rate enhancement was observed.

A practical total synthesis of both enantiomers of epoxyquinols A and B

Abstract A practical total synthesis of both enantiomers of epoxyquinols A and B has been developed. Key reactions are the chromatography-free preparation of an iodolactone by using acryloyl chloride as dienophile in the Diels–Alder reaction of furan, the lipase-mediated kinetic resolution of a cyclohexenol derivative, and a modified procedure for α-iodonation of a cyclohexenone.

Formal total synthesis of fostriecin via 1,4-asymmetric induction using cobalt-alkyne complex

The synthesis of a protected dephosphofostriecin, and thereby a formal synthesis of fostriecin, has been accomplished. Two of the four chiral centers are controlled by an external chiral auxiliary and the other two are synthesized stereoselectively, one by a novel 1,4-asymmetric induction using cobalt-alkyne complex, and the other by 1,3-asymmetric induction.

Reaction modes of oxidative dimerization of epoxycyclohexenols

Abstract Of the 16 possible modes of the oxidation-6π-electrocylization-Diels–Alder reaction cascade for an epoxyquinone, and eight for a 2-alkenyl-3-hydroxymethyl-2-cyclohexen-1-one, only the endo - anti (epoxide) -anti (Me)-hetero and endo - anti (Me)-hetero are respectively observed, while both the endo - anti (epoxide) -anti (Me)-hetero and exo - anti (epoxide) -anti (Me)-homo reaction modes occur with epoxy-4-hydroxycyclohexenones owing to a hydrogen-bonding interaction.

The diastereoselective asymmetric total synthesis of NG-391, a neuronal cell-protecting molecule

Abstract The stereocontrolled total synthesis of (+)-NG-391, a neuronal cell-protecting molecule, is described along with the determination of its absolute stereochemistry. The following reactions in this synthesis are particularly noteworthy: (1) The stereoselective construction of the conjugated (E,E,E,E,E)-pentaene from an (E,E,E)-alcohol using an IBX oxidation followed by stereoselective Horner–Emmons reaction. (2) The (E)-selective Knoevenagel condensation of a β-ketonitrile with a chiral 2-alkoxyaldehyde prepared from (S)-malic acid. (3) A diastereoselective epoxidation.

Epoxyquinol B, a Naturally Occurring Pentaketide Dimer, Inhibits NF-κB Signaling by Crosslinking TAK1

Several epoxyquinoids interfere with NF-κB signaling by targeting IKKβ or NF-κB. We report that epoxyquinol B (EPQB), classified as an epoxyquiniod, inhibits NF-κB signaling through inhibition of the TAK1 complex, a factor upstream of IKKβ and NF-κB. cDNA microarray analysis revealed that EPQB decreased TNF-α-induced expression of NF-κB target genes. EPQB covalently bound to a recombinant TAK1-TAB1 fusion protein in vitro, and inhibited its kinase activity. Furthermore, in vitro/in situ treatment with EPQB resulted in a ladder-like hypershift of TAK1 protein bands. We reported recently that EPQB crosslinks proteins via cysteine residues by opening its two epoxides, and our current results suggest that EPQB inhibits NF-κB signaling by crosslinking TAK1 itself or TAK1 through other proteins.

L-proline-catalyzed enantioselective one-pot cross-Mannich reaction of aldehydes.

This protocol describes a procedure for the synthesis of syn-β-amino α-substituted aldehydes, versatile intermediates in synthetic organic chemistry, via asymmetric, direct, one-pot, three-component, cross-Mannich reaction of two different aldehydes. The reaction consists of two steps; one is the formation of imine by the reaction of aldehyde and p-anisidine in the presence of Pro, and the second step is the enantioselective addition reaction of enamine generated from the other aldehyde and Pro with the imine generated in the first step. As the aldehyde easily racemizes, γ-amino alcohol was isolated and characterized after reduction. The yield and diastereo- and enantioselectivities are generally excellent. It will take approximately 26 h to complete the protocol: 0.5 h to set up the reaction, 20.5 h for the reaction and 5 h for the isolation and purification.