Nobukazu Taniguchi

Aerobic Nickel-Catalyzed Hydroxysulfonylation of Alkenes Using Sodium Sulfinates.

Nickel-catalyzed hydroxysulfonylation of alkenes was achieved using sodium sulfinates under air atmosphere. The procedure enabled the selective synthesis of β-hydroxysulfones in good yields and suppressed the formation of β-ketosulfones. On the contrary, sulfonylation of alkynes with sodium sulfonates afforded only β-ketosulfones.

Stereoselective pinacol coupling of planar chiral (benzaldehyde)Cr(CO)3, (benzaldimine)Cr(CO)3, ferrocenecarboxaldehyde and (dienal)Fe(CO)3 complexes with samarium diiodide

Abstract An intermolecular pinacol coupling of the planar chiral tricarbonylchromium complexes of o-substituted benzaldehydes or benzaldimines with samarium(II) diiodide in THF produces exclusively threo 1,2-diols or 1,2-diamines in an optically pure form, while the corresponding racemic o-substituted benzaldehyde or benzaldimine chromium complexes give a mixture of threo and erythro pinacol coupling products in a various ratio depending upon the nature of o-substituent. Similarly, planar chiral 2-substituted ferrocenecarboxaldehydes and (dienal)Fe(CO)3 produce the corresponding 1,2-diols with high stereoselectivity. The generated transition metal-complexed ketyl radical intermediates are configurationally stable with restriction to a rotation about CαCipso bond.

Oxidative Coupling of Dichalcogenides with Sodium Sulfinates via Copper-Catalyzed Cleavage of S–S and Se–Se Bonds

A copper-catalyzed sulfonylation of disulfides was achieved using sodium sulfinates in air. The reaction formed various sulfur-sulfone bonds efficiently and afforded thiosulfonates in good yields. Selenosulfonates could also be prepared with this procedure. Furthermore, both chalcogenide groups on the dichalcogenides were available in these reactions.

(Arene)tricarbonylchromium complexes in radical reactions: Samarium(II) iodide-mediated coupling of chromium-complexed benzaldehyde or acetophenone with methyl acrylate

Abstract Planar chiral tricarbonylchromium complexes of ortho-substituted benzaldehydes or acetophenones were coupled with methyl acrylate in the presence of samarium(II) iodide to give stereoselectively γ-butyrolactones in good yields.

Planar chiral C2-symmetric bisferrocenes: Stereoselective pinacol coupling of α-substituted ferrocenecarboxaldehydes

Abstract Planar chiral α-substituted ferrocenecarboxaldehydes were treated with samarium diiodide to give stereoselectively pinacol coupling products with a threo -configuration in good yields. The resulting dihydroxyl of the product was substituted with stereochemical inversion by an S N 1 reaction.

Enantiomerenreine cyclischetrans-1,2-Diole, -Diamine und -Aminoalkohole durch intramolekulare Pinakolkupplung planar-chiraler Mono-Cr(CO)3-Komplexe von Biarylen

Keine unerwunschten Stereoisomere liefert die intramolekulare Pinakolreaktion der planar-chiralen Mono-Cr(CO)3-Komplexe 1 von 2,2′-Dicarbonyl-1,1′-biphenylen mit Samariumdiiodid, sondern nur die cyclischen trans-1,2-Diole 2. Nach Einwirkung von Sonnenlicht entstehen aus den Chrom-komplexierten Diolen 2 optisch reine, chromfreie trans-Diole 3. Analog werden die entsprechenden trans-1,2-Diamine und -Aminoalkohole aus den Chromkomplexen von Biphenylen mit Diimino- oder Keto- und Imino-Funktion enantiomerenrein erhalten. R1 = H, OMe; R2 = H, Me; R3 = H, Me.