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- Title
Diastereoselective formation of 18-membered ring BINOL-hydrogen phosphonate dimers - Quasi-covalent hydrogen bonds?
- Authors
Dabbagh, Hossein A.; Noroozi-Pesyan, Nader; Najafi-Chermahini, Ali R.; Patrick, Brian O.; James, Brian R.
- Abstract
Diastereoselective syntheses of the unusual dimers, 4-heptyl-2-(2′-hydroxy-binaphthyl)hydrogen phosphonate (5) and the cyclohexyl analogue (7), are achieved by hydrolysis of 4-(3,5-dioxa-4-phosphacyclohepta[2,1-α;3,4-α′]-dinaphthalene-4-yloxy)heptane (4) and the cyclohexane analogue (6), respectively. Two out of eight possible pairs of monomers units are involved in the stereoselective formation of the dimer 5a of configuration BINOLR-PS:BINOLR-PS; this is determined by X-ray crystallographic data, which reveal a centrosymmetric, 18-membered ring structure with Ci symmetry, consisting of two monomers strongly hydrogen-bonded between the oxygen of P=O units and hydroxyl hydrogen atoms. Mass spectrometric, melting point, and thermal decomposition point data, as well as NMR data, support the presence of strong, quasi-covalent hydrogen bonds. Computational analysis suggests that the diastereoselectivity is controlled by molecularly constrained geometry of the monomer. Compound 7, although not characterized crystallographically, appears to be analogous to 5.
- Subjects
DIMERS; HYDROGEN; HYDROLYSIS; CYCLOHEXANE; MONOMERS
- Publication
Canadian Journal of Chemistry, 2007, Vol 85, Issue 7/8, p466
- ISSN
0008-4042
- Publication type
Article
- DOI
10.1139/V07-060