A convenient stereoselective synthesis of 5-hydroxy-3-oxoesters and 3-hydroxy-5-oxoesters

A biocatalytic approach was employed for the asymmetric reduction of sterically demanding ketones to prepare 3-hydroxy-5-oxo-5-phenylpentanoates and 5-hydroxy-3-oxo-5-phenylpentanoates. Screening a collection of microorganisms led to the identification of stereocomplementary microbial strains that provide access to both enantiomers of 3-hydroxy-5-oxo-5-phenylpentanoates and 5-hydroxy-3-oxo-5-phenylpentanoates with high enantiomeric excess (up to 99% ee). Moreover, the application of Saccharomyces cerevisiae gave two diastereomers of 3,5-dihydroxy-5-phenylpentanoates with high enantiomeric excess (up to 99% ee). The applicability of the identified strains was demonstrated by transforming the obtained dihydroxy ester into the chemically valuable lactone (4S,6R)-tetrahydro-4-hydroxy-6-phenyl-pyran-2-one.     

Synthesis of novel 5-hydroxy-3-alkoxy- and 5-hydroxy-3-alkylthioindole-2-carboxamides

The preparation of several novel 5-hydroxyindole-2-carboxamides is described. A 5-benzyloxyindole ester was elaborated to the 3-bromo, 3-hydroxy, and 3-alkoxy ester intermediates followed by conversion to the amide and debenzylation. A related 5-acetyloxy indole ester was converted to 3-sulfinyl and 3-alkylthio intermediates before simultaneous amidation and removal of the 5-hydroxy protecting group.     

Synthesis and Structure of 3-Aryl-2,4-dibenzoyl-5-hydroxy-5-methylcyclohexanones and 2-Benzoyl-5-hydroxy-5-methyl-3-phenylcyclohexanone

The reaction of benzoylacetone with aromatic aldehydes under basic catalysis conditions afforded 3-aryl-2,4-dibenzoyl-5-hydroxy-5-methylcyclohexanones. The reaction of benzoylacetone with benzalacetone led to the formation of 2-benzoyl-5-hydroxy-5-methyl-3-phenylcyclohexanone.     

A simple TLC and HPTLC method for separation of selected steroid drugs

Chromatographic properties of five steroid drugs: cortisone, hydrocortisone, methylprednisolone, prednisolone and norgestrel have been studied by normal-, reversed-phase and hydrophilic neutral cyano-bonded silica stationary phase with five binary mobile phases (acetonitrile-water, acetonitrile-DMSO, acetonitrile-methanol, acetone-petroleum ether, acetone-water) in which the concentration of organic modifier was varied from 0 to 100% (v/v). This study reports the optimization of steroid hormones separation. Chromatographic retention data and possible retention mechanisms are discussed. Separation abilities of mobile and stationary phases were studied using the principal component analysis method. The best separation of methylprednisolone and prednisolone is with a chromatographic system included silica gel as stationary phase and mixture of acetonitrile and DMSO (10:90 v/v). These two anti-inflammatory drugs can be fast separated from norgestrel when CN is used as stationary phase and acetone and water (40:60 v/v) as mobile phase. The highest values of the parameter Δ(ΔG°) and alfa for cortisone and hydrocortisone was observed in case of using CN as stationary phase and water-acetonitryle (40:60 v/v) as mobile phase.      

A novel thermal rearrangement of the 2-thiabicyclo[3,1,0]hex-3-ene system. The crystal and molecular structure of ethyl-2,4-dichloro-5-hydroxy-6-methylbenzoate

Thermal rearrangement of 1,3-dichloro-6-ethoxycarbonyl-2-thiabicyclo[3, 1, 0]hex-3-ene does not follow the anticipated course, but leads instead to ethyl-2,4-dichloro-5-hydroxy-6-methylbenzoate, whose structure has been confirmed by an X-ray crystal structure determination.     

Novel One Pot Synthesis of 3-Acetyl-5-hydroxy-2-methylbenzofuran and 3-Acetyl-5-hydroxy-2-methylnaphthofuran and Synthesis of Their Derivatives

Abstract

The benzofurans and naphthofurans so far were obtained either by using catalyst or as side products. In the present investigation we are reporting first time the exclusive formation of only 3-acetyl-5-hydroxy-2-methylbenzofuran and 3-acetyl-5-hydroxy-2-methylnaphthofuran in quantitative yield by adopting the Nenitzescu reaction. Further, these 5-hydroxybenzofuran and 5-hydroxynaphthofuran were converted to their corresponding 5-methoxyl/5-methoxycarbonylmethoxy derivatives.     

Regio- and stereoselective electrophilic additions to exo and endo-2-hydroxy-2-methyl-7-oxabicyclo[2.2.1]hept-5-ene

The regio- and stereoselectivity of electrophilic additions of PhSeCl and PhSCl to isomeric 2-hydroxy-2-methyl-7-oxabicyclo[2.2.1]hept-5-enes is highly dependent upon the relative stereochemistry of the substrate.     

Alkyl- and arylamination of 3-hydroxy-4-carbethoxy-5-methylthiophene

N-Alkylaminothiophene derivatives were obtained by the reaction of 3-hydroxy-4-carbethoxy-5-methylthiophene with alkylammonium acetates, while N-arylaminothiophene derivatives were obtained by the reaction of the same thiophene derivative with aromatic amines in the presence of catalytic amounts of iodine.Translated from Khimiya Geterotsilicheskikh Soedinenii, No. 12, pp. 1602–1604, December, 1970.     

Intra- and intermolecular hydrogen bonding in 3-hydroxy- and 5-hydroxychromone

The crystal structures for 3-hydroxychromone and 5-hydroxychromone have been obtained. Both molecules exhibit intramolecular hydrogen bonding between the hydroxy group and the ketone oxygen atom. However, only the 3-hydroxy derivative contains hydrogen bonds between molecules. By comparing the current results with those obtained for the corresponding flavone derivatives, the effect of the B phenyl group on hydrogen bonding is inferred.