V. M. Potapov

Determination of the absolute configuration of the asymmetric nitrogen atom in (+)-D-[SC,RN)-N-methyl-N-isopropyl-α-methyl-benzylaminato-2C,N]-(acetylacetonato-O,O-palladium(II) by x-ray crystallographic analysis

ConclusionsBy x-ray crystallographic analysis of (+)-D-[(SC,RN)-N-methyl-N-isopropyl-o-methyl-benzylaminato-2C,N]-(acetylacetonato-O,O)palladium(II) it was established that with the S configuration of the asymmetric carbon center the adjacent nitrogen atom is fixed in the R configuration during coordination with the metal. Attractive interaction was detected between the H atom of one of the Me groups of theN-isopropyl substituent and the palladium atom. It was shown that it has a stabilizing effect on the ortho-palladized metal ring.

Steric control of the asymmetric synthesis of N-substitued 2-methyl-4-piperidones

Transmission of the iodomethylate of 1,2-dimethyl-4-piperidone by (S)-sec-butylamine gives 1-(S-sec-butyl)-2S-methyl-4-piperidone in 33% optical yield while transamination by (S)-l-methyl-2-phenylethylamine gives a 1:1 diastereomeric mixture of 1-(l-methyl-2-phenylethyl)-2 -methyl-4-piperidone.The decrease in the optical yield is related to the facile opening of the piperidone ring at the C-N bond with subsequent recyclization. The13C MIR data indicate that all the diastereomers of the 4-piperidones obtained are in the chair conformation with predominantly equatorial orientation of the methyl group at C(2). The chiral optical properties were studied and the absolution configurations of the 4-piperidones obtained were established.

Investigation of the three-dimensional structures of a number of N-substituted derivatives of 4-decahydroquinolone by means of 13C NMR spectroscopy

The three-dimensional structures and eonformational compositions of a number of N-substituted 4-decahydroquinolones, particularly the 1-(S)-α-phenylethyl-4-deca-hydroquinolone isomer that is primarily formed in the asymmetric hydride reduction of 1-(S)-α-phenylethyl-Δ9,10-octahydro-4-quinolone and was previously assigned to the trans series on the basis of chiral-optical properties, were investigated by 13C NMR spectroscopy. It is shown by means of NMR data that this compound belongs to the cis series. The lines in the 13C-{1H} NMR spectra of a number of 4-decahydroquinolones were assigned by means of an additive scheme for the 13C chemical shifts, and criteria of the type of fusion of the two rings in the investigated class of heterocyclic compounds were established.

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.

Steric effect of substituents on the nature of the chromophore in ?9,10-octahydro-4-quinolones

The study of the behavior of cisoid two-ring ketones from substituted cyclohexanones and (−)-menthone was continued. The steric effect of a bulky substituent attached to the 8-C atom of the quinolone system on the conformation of the molecule was established; this effect leads to disruption of the conjugation of the p-electron pair of the nitrogen atom in the enamino ketone portion of the chromophore.

Synthesis and chiral-optical properties of some benzolactams

Five- and seven-membered benzolactarns — (−)-S-2, 3-dimethyl-2, 3-dihydroisoindolone and (+)-S-5-methyl-2, 3, 4, 5-tetrahydrobenz[c]azepin-1-one — were synthesized. A study of their chiral-optical properties and comparison with the previously studied six-membered lactam (−)-S-4-methyl-3, 4-dihydroisoquinol-1-one showed that their circular dichroism spectra are similar: The spectra contain dichroic absorption bands due to π → π* transitions in the aromatic chromophore (∼270 and ∼220 nm) and a band of charge transfer in the benzamide chromophore at 240–250 nm. The magnitude of the Cotton effect due to the charge-transfer band increases as the lactam ring becomes larger (five-membered < six-membered < sevenmembered benzolactam). The change in the magnitude of the Cotton effect is explained by the development of a strictly dissymetric chromophore.

Stereochemistry of decahydroquinoline and decahydro-4-quinolone (review)

The configurational and conformational peculiarities of the cis and trans isomers of decahydroquinoline and decahydro-4-quinolone are discussed, and information on a new class of cis-decahydroquinoline alkaloid-neurotoxins and some data on the effect of the three-dimensional structures of decahydroquinoline derivatives on pharmacological activity are presented.

Circular dichroism and configuration of (−)-1-methyl-1,2,3,4,tetrahydroisoquinoline

In the CD (circular dichroism) spectra of (−)-1-methyl-1,2,3,4, tetrahydroisoquinoline, three CE (Cotton effects) are observed in the 300–200 nm region that are due to the absorption bands of the aromatic chromophore. The synthesis of this substance from (S)(−)-α-phenylethylamine and the CD spectra confirm its (S)-configuration.

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.

The 13C NMR spectra, isomerism, and conformational analysis of substituted piperidin-4-ones

The 13C NMR spectra of 15 stereoisomers of 1-mono-, 1,2-di-, and 1,2,5-trisubstituted piperidin-4-ones were investigated, and the stereochemical orientations of the substituents and the conformation relationships were established. For the series of piperidones a method for determination of the absolute confirmation of the C(2) center of the piperidone ring is proposed on the basis of the chemical shifts of the methyl groups in the 1-s-α-phenylethyl substituent at the nitrogen atom in the preferred rotamers with respect to the C(1)-N bond.