Susumu Sato

The first example of aldol reactions between trimethylsilyl enol ethers and aldehydes by the aid of rhodium complex

Abstract Crossed aldol reaction of trimethylsilyl enol ether with aldehyde is successfully performed with the aid of catalytic amount of rhodium complex, [(COD)Rh(DPPB)] + X − (X = PF 6 and ClO 4 ) or Rh 4 (CO) 12 , under neutral conditions.

Rhodium catalyzed direct coupling of αβ-unsaturated ketone, aldehyde, and trialkylsilane: An easy access to regio-defined aldol derivatives

Abstract Regio-defined aldol type compounds are successfully formed by a one-pot reaction of α, β-unsaturated ketones, aldehydes, and Et 2 MeSiH with the aid of a catalytic amount of Rh 4 (CO) 12 or Rh 4 (CO) 12 /MePh 2 P under almost neutral conditions.

Cyclo-codimerization of 1,3-butadiene derivatives with non-activated terminal acetylenes catalyzed by cationic rhodium(i) complex

An efficient cyclo-codimerization between 1,3-diene and non-activatedterminal acetylene has been attained by the catalysis of [Rh(COD)(DPPB)]PF6 to give 1,4-disubstituted cyclohexa-1,3-dienes under mild conditions.

Regiocontrolled synthesis of allylsilanes by means of rhodium(I) or iridium(I) catalyzed isomerization of olefins

Abstract Rhodium(I) or iridium(I) catalyzed migration of double-bond has been successfully applied to the regiocontrolled synthesis of allylsilane from olefin silylated at a remote sp carbon.

A versatile route to silylsubstituted ketones by rhodium catalyzed isomerization of silylated allyl alcohols

Abstract The rhodium catalyzed isomerization of α-, β-, and γ-silylated allyl alcohols has been successfully applied to the selective synthesis of acylsilane, α-silyl ketones, and β-silyl ketones, respectively.

Rhodium(I)- or ruthenium(II)-catalyzed direct coupling of vinyl ketones with aldehydes and the subsequent reduction to give aldol derivatives anti-selectively

Abstract A vinyl ketone reacts with an aldehyde to give an α-methylene-β-hydroxyalkanone with the concomitant formation of the vinyl ketone dimer in the presence of catalytic amount of RhH(PPh 3 ) 4 or RuH 2 (PPh 3 ) 4 under almost neutral conditions. The selectivity of the cross-coupling product is remarkably improved in the presence of an extra mole of aldehyde. This type of cross-coupling is explained by the intermediacy of the transition metal enolate which is formed by the Michael-type addition of Mue5f8H to a vinyl ketone. The subsequent hydrogenation of the carbon—carbon double bond of α-methylene-β-hydroxyalkanone proceeds readily to give aldol derivatives in the presence of the catalyst. [Rh(COD)(DPPB)]PF 6 , [COD = 1,5-cyclooctadiene, DPPB = 1,4-bis(diphenylphosphino)butane] is the best choice of catalyst and gives aldol derivatives anti -selectively. Thus, the two-step operation described provides aldol derivatives by an anti -selective route under almost neutral conditions.

Regio- and stereodefined synthesis of trimethylsilyl enol ethers resulted from the isomerization of α -trimethylsilyl ketones

Abstract The isomerization of an α-trimethylsilyl ketone is lead to the corresponding trimethylsilyl enol ether with the enhanced regioselectivity by heating or by the assist of trimethylsilyl trifluoromethanesulfonate. The thermal reaction discloses a new regiodefined (E)-selective route to silyl enol ethers.

A regiodefined synthesis of α-trimethylsilyl ketones catalyzed by rhodium(I) hydride complex

Abstract Regiodefined synthesis of α-trimethylsilyl ketones is attained by one of three different routes: isomerization of β-trimethylsilyl allyl alcohols (route A), isomerization of β′-trimethylsilyl allyl alcohols (route B), and dehydrogenation of β-trimethylsilyl alcohols via transfer hydrogenation to α,β-enones (route C). All of these procedures are catalyzed efficiently by HRh(PPh 3 ) 4 at about 100 °C. Route A inevitably requires the presence of 2-trimethylsilyl-1-phenyl-2-propen-1-one as a cocatalyst for smooth isomerization. This strongly suggests that a kind of intermolecular transfer hydrogenation plays an important role in the catalytic cycle.

A facile synthesis of α-trimethylsilyl ketones and their regiospecific rearrangement to trimethylsilyl enol ethers

Abstract The rhodium catalyzed isomerization of β-trimethylsilylallyl alcohols has been successfully applied for the stepwise and selective synthesis of α-trimethylsilyl ketones and trimethylsilyl enol ethers.

Aldol-type reactions between trimethylsilyl enol ethers and acetals with the aid of rhodium complex

Abstract Aldol-type reactions of trimethylsilyl enol ethers with acetals, ketals, and orthoesters are successfully performed with the aid of a catalytic amount of rhodium complex, Rh4(CO)12 or [Rh(COD)(DPPB)]+ClO4−, underneutral conditions.