N. N. Romanova

The Use of Microwave Activation in the Chemistry of Heterocyclic Compounds. (Review)

Published data on the successful application of microwave activation in the chemistry of various heterocycles over the last two years are discussed.

Synthesis and stereochemistry of chiral azetidin-2-ones and azetidine-2-thiones. 3. Stereodirected construction of theβ-lactam fragment of the thienamycin molecule

It has been shown possible to introduce an α-hydroxyethyl group trans-stereospecifically into position 3′ of 4-methyl-1-(α-methyl-benzl)azetidin-2-one. The stereochemistry of the asymmetric centers C(3′), C(3), and C(4) of the diastereoisomers of the 3-α-hydroxyethyl derivative obtained in larger amount and of the corresponding three adjacent chiral centers C(8), C(6), and C(5) in thienamycin are the same.

Preparation of opticaly active 3-(1-methyl-1-phenylpropyl)indole and investigation of its chiral-optical properties

Optically active 3-(1-methyl-1-phenylpropyl)indole was obtained by dehydrogenation of the resolved [by means of (L)-10-camphorsulfonic acid] 3-(1-methyl-1-phenylpropyl)indoline. The chiral-optical properties of this product were investigated, and the possibility of the use of circular dichroism data for the identification of the chiral indole chromophore was demonstrated.

Stereochemistry of the methylation of the (11S,4S) and (11S,4R) diastereomers of 4-methyl-1-(?-methylbenzyl)azetidin-2-one

The methylation of the lithium derivatives of the (11S,4S) and (11S,4R) diastereomers of 4-methyl-1-(α-methylbenzyl)azetidin-2-one proceeds stereospecifically with the formation of only trans-(3S,4S)- and trans-(3R,4R)-dimethyl-1-[(S)-α-methylbenzyl] azetidin-2-one, respectively. The process is accompanied by epimerization at the asymmetric center of the N-α-methylbenzyl substituent.

Stereochemistry of electrophilic substitution in β-lactam systems (review)

The literature data on the synthesis of 3-monosubstituted and 3,3-disubstituted β-lactams on the basis of reactions of lithium derivatives of 2-azetidinones with electrophiles are systematized.

Asymmetrical alkylation of 1-[(s)-α-phenylethyl]-azethidinone-2

The methylation of the lithium derivative of azethidinone-2 which has a chiral substituent at the nitrogen atom is asymmetrical and leads, with an optical yield of 35%, to diastereomeric 3-methylated azethidinones-2. The reaction of these compounds with Na in liquid ammonia gives enantiomeric 3-methylazethidinones which confirms that an asymmetrical synthesis has taken place.

Synthesis of 1-(α-phenylethyl)azetidin-2-ones

Phase-transfer catalyzed cyclization of racemic and optically active N-substituted β-aminoacids has given racemic and optically active 2-azetidinones, the spatial structures of which have been established by NMR spectroscopy. The original β-aminoacids were obtained by adding α-phenylethylamine to substituted acrylic acids.

Reaction of indoles with trifluoroacetic acid

Abstract3-Trifluoroacetyl indoles are formed by the action of trifluoroacetic acid on indole-2-carboxylic acid and its benzo-substituted derivatives. When unsubstituted indole is refluxed with trifluoroacetic acid, it gives 3-trifluoroacetylindole in 30% yield.