Aromatic annelation via ∝-oxoketene dithioacetals:synthesis of thioresorcinol dimethyl ethers

A novel aromatic annelation leading to fused thioresorcinol dimethylethers has been developed by reacting cyclic ∝-oxoketene dithioacetals with propargylmagnesium bromide followed by treatment of the resulting carbinolacetals with borontrifluoride etherate in methanol.     

Cycloaromatization of ∝-oxoketene dithioacetals with 3-methyl-5-lithiomethylisoxazole: A new general approach for synthesis of substituted and annelated 1,2-benzisoxazoles

A new general method for the synthesis of substituted and annelated 1,2-benzisoxazoles has been developed by cycloaromatization of ∝-oxoketene dithioacetals with 3-methyl-5-lithiomethylisoxazole.     

Novel cycloaromatization in reformatsky reaction on ∝-oxoketene dithioacetals: A regioselective synthesis of substituted ethyl 2-hydroxy-6-methylthiobenzoates

A novel cycloaromatization reaction leading to substituted ethyl 2-hydroxy-3-methylthiobenzoates $\text{6}$ by condensation ∝-oxoketene dithioacetals $\text{1}$ with excess of Reformatsky reagent $\text{2}$ from ethyl bromoacetate through intermediate dienes 3 has been reported.     

Synthesis of α-pyrones from α-oxo ketene dithioacetals

α-Oxo ketene dithioacetals can be converted into α-pyrones in a three step process involving 1,2-nucleophilic addition of ester or ketone enolate anions, acid promoted rearrangement, and subsequent enol lactonization. Utilization of ester enolates affords 6-alkylthio α-pyrones while ketone enolates give 3-alkyl substituted α-pyrones.     

Divergent reactivity of α-oximino carbenoids: facile access to 2-isoxazolines and 2H-azirines

Mild catalytic reaction conditions for the synthesis of 2-isoxazolines and 2H-azirines have been developed via carbenoids derived from α-oximino diazo compounds. This has been utilized in the one-pot synthesis of pyrroles in the presence of 1,3-dicarbonyl compounds.     

Anionic cyclizations of aromatic ester dithioacetals with facially biased α,β-unsaturated ketones

Cyclopent-2-enones bearing a plane-nonsymmetric oxygen function on C-4 reacted efficiently with anions derived from aromatic ester dithioacetals to provide annulated products in a highly diastereoselective fashion. Whereas the anion of a dimethoxy aromatic ester dithiolane more rapidly reacted by an alternative intramolecular pathway, the anion of the corresponding aromatic ester dithiane was suitable for the intermolecular cyclization.     

Photoreaction of α-phenylcrotononitrile derivatives: the facile cyclopropane ring formation

Irradiation of 4-methyl, 4,4-dimethyl, and 4,4,4-trimethyl derivatives of 2-phenylcrotononitrile gives the corresponding 1-cyano-1-phenylcyclopropanes in high yields.     

The cation exchange resin-promoted coupling of alkynes with aldehydes: one-pot synthesis of α,β-unsaturated ketones

Alkynes undergo smooth coupling with aldehydes in the presence of Amberlyst-15^® at room temperature to produce the corresponding α,β-unsaturated ketones in high yields with E-geometry. The use of an inexpensive, readily available, and recyclable cation exchange resin makes this method quite simple and convenient.     

DBSA-catalyzed hydrolysis of chain α-oxo ketene dithioacetals in water: Aqueous synthesis of β-ketothioesters

In this paper, we wish to report an environment friendly synthetic method for β-ketothioesters from a dodecylbenzenesulfonic acid (DBSA)-catalyzed hydrolysis reaction of chain α-oxo ketene dithioacetals in water. It was shown that the hydrolysis reaction of chain α-oxo ketene dithioacetals could efficiently occur in the presence of 7.5?mol% DBSA at 100?°C in water, affording the desired β-keto thioesters in excellent yields.     

A facile method for the synthesis of enantiopure α-unsubstituted β-hydroxy esters

One-pot deacylation–debromination reactions involving the transesterification of the initial chiral α-bromo-β-hydroxy thioimide aldol adducts and subsequent Al–Hg mediated reductive cleavage of the C–Br bond allow for a facile synthesis of enantiopure β-hydroxy esters.     

A facile synthesis of α-aminophosphonates catalyzed by ytterbium perfluorooctanoate under solvent-free conditions

Three-component reactions of aldehydes, amines and diethyl phosphite are efficiently catalyzed by ytterbium perfluorooctanoate [Yb(PFO)₃] under solvent-free conditions, giving the corresponding α-aminophosphonates in good to excellent yields. The catalyst can be recovered and reused for several times without any significant loss of activity. Furthermore, a possible mechanism for this transformation is also presented.     

A facile synthesis of bicyclic α-methylene-γ-lactones by intramolecular cyclization of allylsilylated aldehydes

Bicyclic α-methylene-γ-lactones were synthesized employing intramolecular reaction of an aldehyde unit with a β-ethoxycarbonylallylsilane function by the action of TiCl₄ in an excellent yield.     

A facile pathway to 2-furfurylketones

2-(Chloromethyl)furan as an electrophile reacted with lithium trialkylalkyllylbo-rates,followcl by the oxidation with H_2O_2 under basic condition to afford 2-furfurylketonesin good yields.This provides a new method for the preparation of 2-furfurylkctoncs.     

A dinuclear palladium catalyst for α-hydroxylation of carbonyls with O2

A chemo- and regioselective α-hydroxylation reaction of carbonyl compounds with molecular oxygen as oxidant is reported. The hydroxylation reaction is catalyzed by a dinuclear Pd(II) complex, which functions as an oxygen transfer catalyst, reminiscent of an oxygenase. The development of this oxidation reaction was inspired by discovery and mechanism evaluation of previously unknown Pd(III)-Pd(III) complexes.     

A facile transformation of alkynes into α-amino ketones by an N-bromosuccinimide-mediated one-pot strategy

A facile efficient transformation of commercially available alkynes into α-amino ketones by an N-bromosuccinimidemediated one-pot cascade strategy was developed. A variety of α-amino ketones were obtained in moderate to good yields under mild conditions.     

1:1 and 1:2 Inclusion Complexes of Di-tert-butyl l-tartrate with α-Cyclodextrin: A Diffusion Study

The diffusion properties at two overall compositions of a ternary aqueous system containing α-cyclodextrin and a double-functional guest molecule, namely di-tert-butyl l-tartrate, have been studied by means of the Gouy interferometry. The experimental data are interpreted in terms of two independent chemical equilibria involving inclusion compounds. The elements of the diffusion coefficient matrix have been expressed as functions of the two equilibrium constants as well as of the diffusivities of the actual species occurring in solution. The reliability of the diffusion coefficients obtained through the Fujita–Gosting–Revzin procedure is also discussed in terms of its dependence on the composition of solutions used in the Gouy experiments.     

A facile synthesis of per (poly )fluoroalkyl substituted α-amino acid derivatives

Initiated by CrCl3/Fe redox couple, per(poly)fluoroalkyl iodides added to methyl a-acetylamino acrylate, giving B-per(poly)fluoroalkyl a-amino acid derivatives in good yields.     

A new facile synthesis of α-dicarbonyl compounds by oxidation of alkynes with Mo(VI) peroxocomplex promoted by mercuric acetate

Mercuric acetate promoted oxidation of diaryl-, dialkyl-, and aralkyl alkynes with (HMPA)MoO(O₂)₂ in 1,2-dichloroethane affords the corresponding α-diketones in good yields. Likewise, terminal alkynes can be converted into α-ketoaldehydes in excellent yields by using the same oxidizing system.