V. M. Dem'yanovich

Stereoselective synthesis of 1,3-disubstituted phthalans by cyclization of (1S)-1-{2-[hydroxy(diaryl)methyl]phenyl}ethanols

Cyclization of pure enantiomers of 1-{2-[hydroxy(diaryl)methyl]phenyl}ethanol proceeds stereoselectively and affords 1,3-disubstituted 1,3-dihydroisobenzofurans (phthalans) in moderate-to-high enantiomeric (81.7% ee) or diastereomeric (72% de) purity.

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.

Chiral-optical properties of six- and seven-membered benzothioamides

The chiral-optical properties of R-(+)-4-methyl-3,4-di-hydroisoquinoline-1-thione and R-(-)-3-methyl-, R-(+)-4-methyl-, and S-(+)-5-methyl-2,3,4,5-tetrahydrobenz[c]-azepine-1-thiones were studied. A significant increase in the intensities of the Cotton effects (CE), particularly for the CE due to the n → π* transition in the benzothioamide chromophore, is observed on passing from six-membered to seven-membered benzothiolactams with the same orientation of the asymmetric center relative to the chromophore. The signs of the CE due to the n → π* transition in the benzothioamide chromophore and the π → π* transition in the aromatic chromophore at 250–280 nm (the 1Lb band) correlate with the type of conformation of the thiolactam ring.

Influence of structure on the circular dichroism of methyl-substituted 1,3,4-tetrahydrobenz[b]azepin-2-ones

The chirooptical properties of methyl-substituted 1,3,4,5-tetrahydrobenz[b]azepin-2-ones have been studied. A considerable increase in the intensity of the Cotton effect (CE) in the 240–250 nm region with an enlargement of the lactam ring has been observed. The sign of this CE for seven-membered benzolactams correlates with the type of conformation of the lactam ring. A change in the nature of the conjugation (passage from lactams of the benzamide type -C6H4-CO-NH- to lactams of the anilide type -C6H4-NH-CO-) leads to an inversion of the signs of the CEs in the 230–250-nm region.

Intramolecular amidation of arylalkylhydroxamic acids

It is shown that mixtures of two isomeric benzolactams, viz., compounds of the benzamide and anilide type, are formed in the intramolecular amidation of arylalkylhydroxamic acids under the influence of polyphosphoric acid (PPA). A general reaction scheme that includes three pathways, viz., direct amidation, Lossen rearrangement of the hydroxamic acids with subsequent cyclization of the isocyanates, and Beckmann rearrangement of the oximes of the cyclic ketones formed in the thermal cleavage of the starting hydroxamic acids in PPA, is proposed on the basis of a study of racemic and optically active arylalkylhydroxamic acids.