Asymmetric synthesis of beta-hydroxy sulfides controlled by remote sulfoxides

Reactions of (S)-alpha-(methylthio)-2-(p-tolylsulfinyl)benzyl carbanion with different carbonyl compounds proceeds with complete control of the configuration at the benzylic position. Aldehydes yield easily separable mixtures of beta-hydroxy sulfides, epimers at the hydroxylic carbon, where the stereoselectivity depends on steric factors (from 20% to >98% de).     

Highly regioselective rearrangement of 2-substituted vinylepoxides catalyzed by gallium(III) triflate

Gallium(III) triflate catalyzed the rearrangement of 2-substituted vinylepoxides into beta,gamma-unsaturated carbonyl compounds with high regio- and chemoselectivity (>97/3) in low catalyst loading (1-5 mol %). The alkyl-substituted trimethylsilylvinyl epoxides gave beta,gamma-unsaturated ketone, but aryl-substituted vinylepoxides gave the aldehydes instead.     

A general and selective zinc-catalyzed oxidation of sulfides to sulfoxides

A general zinc-catalyzed oxidation of sulfides to sulfoxides has been developed. All the reactions proceeded at room temperature. Hydrogen peroxide was used as a green oxidant. Twenty-one examples of sulfoxides were prepared in moderate to excellent yields.     

Highly efficient one-pot synthesis of primary amides catalyzed by scandium(III) triflate under controlled MW

The present Letter highlights a versatile synthetic protocol for the one-pot synthesis of primary amides employing scandium(III) triflate as a catalyst in water under controlled MW. This methodology offers excellent yields in shorter reaction times with enhanced selectivity.     

Gold(III) catalyzed oxidation of sulfides to sulfoxides with hydrogen peroxide

Au(III) catalyzed oxidation of sulfides to sulfoxides with 30% hydrogen peroxide in good yields and chemoselectivities was developed. It was shown that the catalyst loading can be decreased to 0.01 mol % with the good activity and chemoselectivity. Meanwhile, the catalyst was stable in the reaction system, which can be reused at least six cycles with similar activity and chemoselectivity.     

Highly efficient and versatile acetylation of alcohols catalyzed by cerium(III) triflate

Cerium(III) triflate is a powerful catalyst for the acetylation of alcohols. The reaction works well for a large variety of simple and functionalized alcohols, without isomerisation of chiral centres. Changes of hydroxyl protective groups are possible in a one-pot procedure. The catalyst can be easily recycled.     

A highly efficient reusable homogeneous copper catalyst for the selective aerobic oxygenation sulfides to sulfoxides

Readily available copper showed efficient activity and great selectivity for the homogeneous catalysis of oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant. The reaction proceeds under mild conditions in the presence of a catalytic amount of TEMPO. Importantly, the catalysts could be conveniently recovered and reused. And this methodology was proved to be applicable for the transformation of various aromatic and aliphatic sulfides into the corresponding sulfoxides with high conversion and high selectivity.     

Mild and efficient method for the cleavage of benzylidene acetals by using erbium (III) triflate

Er(OTf)3 is proposed as new efficient Lewis acid catalyst in a mild deprotection protocol of benzylidene derivatives. In a modified procedure, where acetic anhydride is used as the reaction solvent, the simultaneous cleavage of the benzylidene acetal and the peracetylation of the substrates is obtained in quantitative yields and very short reaction times.     

Stereoselective synthesis of tetrahydropyran-4-ones from dioxinones catalyzed by scandium(III) triflate

[reaction: see text] A scandium triflate catalyzed, diastereoselective cyclization between aldehydes and beta-hydroxy dioxinones has been discovered. This process capitalizes on the untapped nucleophilicity of the embedded enol ether within the dioxinone core. The bicyclic compounds from the resulting cyclization can be isolated, or alternatively, alkoxide nucleophiles can be directly added. This in situ addition fragments the dioxinone rings and delivers the 3-carboxy-substituted tetrahydropyran-4-ones in good yields with high levels of diastereoselectivity.     

A highly efficient d-fructofuranosylation catalyzed by scandium(III) triflate

This Letter describes a highly efficient d-fructofuranosylation catalyzed by scandium(III) triflate. The benzylated and benzoylated d-fructofuranosyl acetate derivatives worked as good reactive donors in the presence of only 5 mol % scandium(III) triflate at 0 °C in toluene to afford the d-fructofuranosides in excellent yields. The fructofuranosylation also produced several non-reducing disaccharides of sucrose mimics using several aldopyranose derivatives as the acceptors.     

Efficient one-pot synthesis of α-aminophosphonates from aldehydes and ketones catalyzed by ytterbium(III) triflate

An efficient three component one-pot synthesis of N-silylated α-aminophosphonates and α,α-disubstituted α-aminophosphonates was developed using Yb(OTf)₃ as a catalyst at room temperature under mild conditions.     

Selective synthesis of sulfoxides and sulfones by tantalum(V) catalyzed oxidation of sulfides with 30% hydrogen peroxide

The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride in acetonitrile, i-propanol, or t-butanol selectively provided the corresponding sulfoxides in high yields. On the other hand, the reaction of sulfides with 30% hydrogen peroxide-catalyzed by tantalum(V) chloride or tantalum(V) ethoxide in methanol effectively gave the sulfones.     

A facile synthesis of 2,3-dihydro-2-aryl-4（1H）-quinazolinones catalyzed by scandium（Ⅲ） triflate

2,3-Dihydro-2-aryl-4(1H)-quinazolinones were prepared in good yields via condensation of o-aminobenzamide with aldehydes promoted by a catalytic amount of Sc(OTf)_3 under mild conditions.     

A highly selective method for the synthesis of 1,3-diarylbenzo[f]quinoline derivatives catalyzed by silver triflate

Abstract  

The three-component reactions of aromatic aldehydes, naphthalen-2-amine, and phenylacetylene catalyzed by AgOTf in toluene selectively gave 1,3-diarylbenzo[f]quinolines in high yields. This procedure provides an efficient method for the synthesis of benzo[f]quinolines under mild reaction conditions and with high yields, high selectivity, and operational simplicity.     

Highly efficient and versatile chemoselective addition of amines to epoxides in water catalyzed by erbium(III) triflate

Er(OTf)₃ is proposed as a highly efficient and reusable catalyst for the opening of epoxides in water with aliphatic as well as aromatic amines leading to the synthesis of β-amino alcohols. The aqueous conditions employed in the present method will make it ‘environmentally friendly’ and potentially useful for industrial applications.     

Environment friendly organic synthesis using bismuth compounds. An efficient method for carbonyl-ene reactions catalyzed by bismuth triflate

Bismuth triflate (0.1 mol %) is a highly efficient catalyst for the cyclization of citronellal 1, a reaction that yields a ratio of 80:20 of isopulegol 2 and neoisopulegol 3. This methodology has also been extended to the synthesis of substituted piperidines. The bismuth triflate catalyzed ene reaction of aldehyde 4 gives a 70:30 mixture of piperidines 5 and 6. The advantages of these methods include the use of a highly efficient catalyst that is relatively nontoxic, cheap and easy to handle.