L. D. Solov'eva

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.

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.

Mass-spectral behavior of benzothiolactams and isomeric ?-arylalkyl isothiocyanates

The corresponding five benzothiolactams were obtained by cyclization of racemic arylalkyl isothiocyanates in polyphosphoric acid. The fragmentation of all five pairs of isomeric compounds under the influence of electron impact was investigated thoroughly.

Differences in the mass spectra of isomeric benzolactams

It is shown that 3- and 4-substituted dihydro-2-quinolones can be distinguished from the isomeric dihydro-1-isoquinolones by mass spectrometry. The [M - CO]+ ion is characteristic for the mass spectra of dihydroquinolone derivatives, whereas retrodiene fragmentation of the molecular ion is characteristic for dihydroisoquinolone derivatives. The intense [M - R]+ and [M - R, - H2O]+ ion constitute evidence that the substituent is located in the 3 (for dihydroisoquinolones) or 4 (for dihydroquinolones) position. The processes that occur in the fragmentation were confirmed by data from the high-resolution mass spectra, an analysis of the observed metastable ions, and an analysis of the mass spectra of 3-methyl-3,4-dihydro-1-isoquinolone and 4-methyl-3,4-dihydro-2-quinolone containing deuterium attached to the nitrogen atoms.

Synthesis and chiral-optical properties of (+)-3-methyl-3,4-dihydroisoquinoline-1-thione

Abstract(+)-3-Methyl-3,4-dihydroisoquinoline-1-thione was obtained by sulfuration of (+)-3-methyl-3,4-dihydroisoquinolone with phosphorus pentasulfide or by cyclization of (+)-α-benzylethyl isothiocyante under the influence of polyphosphoric acid. Measurements of the rotatory dispersion and circular dichroism showed the presence of two positive Cotton effects due to n→π* and π→π* transitions in the thioamide chromophore, as well as Cotton effects apparently due to π→π* transitions in the aromatic chromophore.