Chiral 7-Oxabicyclo[2.2.1]heptane Building Blocks for Prostanoids

Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular...     

β-Lactam Ring Opening in the Reformatsky Reaction of (3R,4R)-4-Acetoxy-3-((1R)-1-{[tert-butyl(dimethyl)silyl]oxy}ethyl)azetidin-2-one with Ethyl 4-Bromo-3-oxopentanoate

Russian Journal of Organic Chemistry - The Reformatsky reaction of (3R,4R)-4-acetoxy-3-((1R)-1-{[tert-butyl(dimethyl)silyl]oxy}ethyl)­azetidin-2-one with ethyl 4-bromo-3-oxopentanoate gave...     

Regioselective Intermolecular Cyclization of Methyl (E)-3-[(4S,5S)-5-Acetyl-2,2-dimethyl-1,3-dioxolan-4-yl)]prop-2-enoate

Russian Journal of Organic Chemistry - Methyl (E)-3-[(4S,5S)-5-acetyl-2,2-dimethyl-1,3-dioxolan-4-yl)]prop-2-enoate obtained from D-ribose eliminates water on storage and transforms into a bicyclic...     

New Azetidinone Building Block for Carbapenems

Russian Journal of Organic Chemistry - A new versatile building block for the synthesis of carbapenems,...     

Synthesis of β-Lactam and Anomalous Minor Products in the (<Emphasis Type="Italic">i</Emphasis>-Pr)<Subscript>2</Subscript>NEt-Promoted Reaction of <Emphasis Type="Italic">N</Emphasis>-Chloroglycine Methyl Ester Derivative with Dichloroacetyl Chloride

Apart from the expected [2 + 2]-cycloaddition product, the reaction of N-chloro-N-(2-methoxy-2-oxoethyl)-β-alanine methyl ester with dichloroacetyl chloride in the presence of ethyl(diisopropyl)amine gave minor N-(1,2-dichloro-2-oxoethyl)-β-alanine methyl ester and (3E)-1,1,1-trichloro-4-(diisopropylamino)- but-3-en-2-one.     

Chiral blocks for the synthesis of cyclopentanoids from [2 + 2]-cycloadduct of dichloroketene and dimethylfulvene

Opening of the α,α-dichlorocyclobutanone ring in the [2 + 2]-cycloadduct of dichloroketene and dimethylfulvene with (+)-α-methylbenzylamine gave diastereoisomeric 2-dichloromethyl-5-isopropylidene-N-(α-methylbenzyl)cyclopent-3-ene-1-carboxamides, and hydrolysis of the latter at the dichloromethyl group afforded the corresponding bicyclic aminals which can be readily separated by chromatography on silica gel. The subsequent removal of the α-methylbenzylamine fragment via reduction and hydrolysis resulted in the formation of enantiomerically pure (-)- and (+)-6-(1-methylethylidene)-3,3a,6,6a-tetrahydro-1H-cyclopenta[c]-furan-1-ones.     

Red and green chemiluminescence of Na, Mg, and lanthanide triphenylmethyl derivatives during oxidation by dioxygen and cerium(IV)

Chemiluminescence (CL) of triphenylmethyl organometallics (TPM), Ph₃CNa, Ph₃CMgCl, and Ph₃CLnCl₂ (Ln=Cd, Eu, and Dy), in THF and toluene during oxidation by O₂ and the (NH₄)₂Ce(NO₃)₆ complex was found. The first CL is caused by the luminescence of two emitters: (Ph₃C)^*, emitting in the green spectral region (λ_max=524, 550 nm), and an unstable product of substitution of the hydrogen atom in the phenyl ring of the Ph₃C radical, emitting in the red region (λ_max=580±20 nm). The emitter of the second CL, Ph₃C^.*, is generated in the elementary electron transfer from the Ph₃C⁻ anion to Ce^IV, reducing the latter to Ce^III. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1102–1105, June, 1999.     

Structure and catalytic activity of α-chymotrypsin in solutions of gemini surfactants

The regulatory effect of gemini alkylammonium surfactants (GSurf) with the hexamethylene spacer varying in the length of alkyl radicals on the structure and catalytic activity of a-chymotrypsin was studied. A correlation between the activity of a-chymotrypsin and the length of the alkyl radical of GSurf was found. Gemini surfactants enhance the enzyme activity below the critical micelle concentration (CMC) and inhibit that above the CMC. The results of IR spectroscopy and the data on tryptophan fluorescence show that the interaction of GSurf with a-chymotrypsin induces changes in the protein structure differed in intensity. The most probable enzyme complexes with GSurf were characterized by the molecular docking method.