General Synthesis of meso-1,4-Dialdehydes and Their Application in Ir-Catalyzed Asymmetric Tishchenko Reactions.

A practical synthesis of meso-1,4-dialdehydes based on the oxidative cleavage of cyclobutanediol derivatives using polymer-supported periodate was developed. The meso-1,4-dialdehydes were obtained in up to >99% yield and subsequently employed in Ir-catalyzed asymmetric Tishchenko reactions to give the corresponding chiral lactones, which are versatile synthetic intermediates, in good yield with moderate enantiomeric excess. The catalytically active species was identified by means of cold-spray ionization mass spectrometry and 1H NMR spectroscopy.

Accumulation of squalene in filamentous fungi Trichoderma virens PS1-7 in the presence of butenafine hydrochloride, squalene epoxidase inhibitor: biosynthesis of 13C-enriched squalene.

Squalene is a triterpenoid compound and widely used in various industries such as medicine and cosmetics due to its strong antioxidant and anticancer properties. The purpose of this study is to increase the accumulation of squalene in filamentous fungi using exogeneous butenafine hydrochloride, which is an inhibitor for squalene epoxidase. The detailed settings achieved that the filamentous fungi, Trichoderma virens PS1-7, produced squalene up to 429.93 ± 51.60 mg/L after culturing for 7 days in the medium consisting of potato infusion with glucose at pH 4.0, in the presence of 200 µm butenafine. On the other hand, no squalene accumulation was observed without butenafine. This result indicated that squalene was biosynthesized in the filamentous fungi PS1-7, which can be used as a novel source of squalene. In addition, we successfully obtained highly 13C-enriched squalene by using [U-13C6]-glucose as a carbon source replacing normal glucose.

Using α- and ß-Epimerizations of cis-2,3-Bis(hydroxymethyl)-γ-butyrolactone for the Synthesis of Both Enantiomers of Enterolactone.

In the context of asymmetric synthesis, epimerization is usually problematic. Here, we describe the use of the epimerization of cis-2,3-bis(hydroxymethyl)-γ-butyrolactone for the synthesis of enterolactones with anti-carcinogenic, anti-inflammatory, anti-angiogenic, and antioxidant activity. Selective α- or ß-epimerization of a γ-butyrolactone was used to selectively synthesize both enantiomers of enterolactone. Theoretical and kinetic studies were performed to elucidate the epimerization mechanism.

Catalytic enantioselective intramolecular Tishchenko reaction of meso-dialdehyde: synthesis of (S)-cedarmycins.

The first successful example of a catalytic enantioselective intramolecular Tishchenko reaction of a meso-dialdehyde in the presence of a chiral iridium complex is described. Chiral lactones were obtained in good yields with up to 91% ee. The obtained enantioenriched lactones were utilized for the first synthesis of (S)-cedarmycins A and B.

Helically Chiral 1-Sulfur-Functionalized [6]Helicene: Synthesis, Optical Resolution, and Functionalization.

The synthesis and optical resolution of helically chiral 5,6,9,10-tetrahydro-1-[6]helicenethiol and its subsequent transformations to enantiopure 1-sulfur-functionalized [6]helicenes are reported. A novel enantiopure [7]thiahelicene having a thiophene ring at the terminal position of the [6]helicene skeleton was synthesized.

One-Pot Catalysis Using a Chiral Iridium Complex/Brønsted Base: Catalytic Asymmetric Synthesis of Catalponol.

Tandem asymmetric hydrogen transfer oxidation/aldol condensation under relay catalysis of a chiral iridium complex/achiral Brønsted base binary system is described for the synthesis of α-benzylidene-γ-hydroxytetralones with high ee's. A two-step synthesis of catalponol was achieved using this sequential methodology together with regio- and stereoselective hydroboration.

The crystallographic study of left-handed Z-DNA d(CGCGCG)2 and thermine complexes crystallized at various temperatures and at various concentration of cations.

In crystals of complexes of thermine and d(CGCGCG)2 molecules grown at 4, 10, and 20 degrees C, the numbers of thermine molecules connected to the DNA molecule were dependent on the temperature of the crystallization. Two molecules of thermine and one Mg2+ ion were connected to DNA molecule when thermine and d(CGCGCG)2 were co-crystallized at 4 and at 20 degrees C. When an increased concentration of magnesium and thermine molecules were co-crystallized with d(CGCGCG)2 molecules at 10 degrees C, three Mg2+ ions and only one thermine molecule were bound with a d(CGCGCG)2 molecule. The number of polyamines and of Mg2+ ions connected to DNA was dependent on the atomic values of the polyamine and of the metal ion. The binding of more Mg2+ ions occurred when the atomic value of Mg2+ exceeded that of the corresponding mono- or polyamine, and when the Mg2+ ion concentration was elevated. Furthermore, this study is the first documentation of a naturally occurring polyamine bound to the minor groove of DNA in a crystal structure.

Polyamines stabilize left-handed Z-DNA: using X-ray crystallographic analysis, we have found a new type of polyamine (PA) that stabilizes left-handed Z-DNA.

There are many great reports of polyamine stabilization of the Z-DNA by bridge conformation between neighboring, symmetry-related Z-DNA in the packing of crystals. However, polyamine binding to the minor groove of Z-DNA and stabilizing the Z-DNA structure has been rarely reported. We proved that the synthesized polyamines bind to the minor groove of Z-DNA and stabilize the conformation under various conditions, by X-ray crystallographic study. These polyamines consist of a polyamine nano wire structure. The modes of the polyamine interaction were changed under different conditions. It is the first example that the crystals consisted of metal free structure. This finding provides a basis for clarifying B-Z transition mechanics.

Ruthenium-catalyzed cyclocarbonylation of allenyl alcohols and amines: selective synthesis of lactones and lactams.

Allenyl alcohols such as 4-hydroxybuta-1,2-dienes and 5-hydroxypenta-1,2-dienes having a variety of substituents undergo cyclocarbonylation in the presence of a ruthenium catalyst under mild conditions selectively to give five- and six-membered lactones in a high yield with 100% atom economy. 5-Aminopenta-1,2-dines are also cyclocarbonylated to give gamma-lactams. A possible carbonylation mechanism involving a ruthenium cluster intermediate is proposed on the basis of experimental results.

Ruthenium-catalyzed carbonylation of allene: direct synthesis of methacrylates and methacrylamides.

Carbonylation reactions of allene in alcohols and amines in the presence of a ruthenium carbonyl catalyst under mild conditions gave methacrylates and methacrylamides, respectively, in good yields with an atom economy of 100%.