Organic crystal engineering with 1,4-piperazine-2,5-diones. 6. Studies of the hydrogen-bond association of cyclo[(2-methylamino-4,7-dimethoxyindan-2- carboxylic acid)(2-amino-4,7-dimethoxyindan-2-carboxylic acid)]

Robin A. Weatherhead-Kloster, Hugh D. Selby, Walter B. Miller, Eugene A. Mash

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

The title 1,4-piperazine-2,5-dione was synthesized in 23% yield over six steps from ethyl 2-amino-4,7-dimethoxyindan-2-carboxylate. Crystallization by slow diffusion of ether into a chloroform solution and by slow evaporation of an ethanol-chloroform-benzene solution produced polymorphic crystalline forms as determined by single-crystal X-ray analysis. The polymorphs exhibited different hydrogen-bonding networks. The association of this piperazinedione in solution was studied using mass spectrometric and nuclear magnetic resonance spectroscopic techniques. The MS and NMR data were interpreted using the solid-state structures as models for solution aggregation. Association constants extracted from the NMR data are in line with those of other cyclic cis amides in chloroform solvent.

Original languageEnglish (US)
Pages (from-to)8693-8702
Number of pages10
JournalJournal of Organic Chemistry
Volume70
Issue number22
DOIs
StatePublished - Oct 28 2005

ASJC Scopus subject areas

  • Organic Chemistry

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