Conformational studies on 1,3-dioxepans. Part II. 1,3:2,5:4,6-Tri-O-ethylidene-D-mannitol and some related compounds
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 623-626
- https://doi.org/10.1039/j29690000623
Abstract
1,3:2,5:4,6-Tri-O-ethylidene-D-mannitol and 2,5-O-ethylidene-1,3:4,6-di-O-methylene-D-mannitol exist in one stable configuration. On the basis of n.m.r. studies and the comparative stabilities of the twist-chair (TC), twist-boat (TB), and chair (C) conformations for a seven-membered ring, it is suggested that the 1,3-dioxepan rings exist predominantly in the TC form. The chemical shift data for the O-ethylidene methine and methyl protons in the 1,3-dioxan and dioxepan rings of the above-mentioned derivatives and of 1,3:4,6-di-O-ethylidene-2,5-O-methylene-D-mannitol are compared.Keywords
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