Autoassembly of cage structures. 4. Stereochemistry of 2,5-di-tert-butyl-γ-butyrolactone-4-carboxy-s-(α)-phenylethylamide

I. V. Vystorop, A. B. Zolotoi, V. M. Anisimov, V. G. Kartsev, R. G. Kostyanovskii

Research output: Contribution to journalArticlepeer-review

Abstract

The diastereoisomeric lactonamides (2a, b), obtained from the dilactone (1) and S-phenylethylamine, have been separated. X-ray crystallography shows that the high-melting isomer (2a) has the R-configuration at the chiral centers C2 and C4, the enantiomeric conformation of the γ-lactone ring being of the S-type in the twist form, intermediate between envelope2E and semi-chair32T. It is shown by molecular mechanics that the minimum steric energy of 2a corresponds to a conformation of the heterocycle close to the envelope form3E. Examination of van der Waals interactions shows that the calculated structure for 2a is preferred. The reasons for the nonidentity of the forms of the γ-lactone ring of 2a in the crystal and the free state are discussed. The crystal structure of 2a is composed of two geometrically similar independent molecules associated along the axis by weak hydrogen bonds of two types, the energies of which have been estimated from the vXH values, which are related by the expression vXH=f(RX...O), where X=N, O.

Original languageEnglish (US)
Pages (from-to)1235-1243
Number of pages9
JournalBulletin of the Russian Academy of Sciences Division of Chemical Science
Volume41
Issue number7
DOIs
StatePublished - Jul 1 1992
Externally publishedYes

Keywords

  • H andC NMR spectrum
  • IR and mass spectra
  • absolute configuration
  • diastereoisomeric lactonamides
  • enantiomeric conformations
  • folding parameters
  • hydrogen bonds
  • molecular mechanics
  • stereochemistry
  • x-ray crystallography

ASJC Scopus subject areas

  • Chemistry(all)

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