Proton magnetic resonance studies of compounds with bridgehead nitrogen. Part 34. Stereochemistry of 8,9,10,11,11a,11b,12,13-octahydro-7aH-quino[1,2-c][1,3]benzoxazines and 7a,8,9,10,10a,10b,11,12-octahydrocyclopent[5,6][1,3]oxazino[3,4-a]quinolines
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 12,p. 1592-1601
- https://doi.org/10.1039/p29770001592
Abstract
Four diastereoisomeric 8,9.10,11,11a,11b.12,13-octahydro-7aH-quino[1,2-c][1,3]benzoxazines and two 7a.8,9,10,10a,10b.11,12-octahydrocyclopent[5,6][1,3]oxazino[3,4-a]quinolines have been synthesised and their configurations assigned by 1H n.m.r. spectroscopy. In the case of the quinobenzoxazines the r-7a,c-11a,c-11b compound adopts the trans-BC conformation, the r-7a,t-11a,c-11b- and the r-7a,c-11a,t-11b-compounds both exist predominantly in the trans-Bc conformations, and the r-7a,t-11a,t-11b-compound predominantly adopts the cis-BC-O-outside conformation. Similar conformational preferences are exhibited by the r-7a,c-l0a,c-10b- and the r-7a,t-10a,c-10b-cyclopenta-analogues. 4,4a,5,6 -Tetrahydro-3H-[1,3]oxazino[3,4-a]quinoline and its 3methyl derivatives all adopt predominantly the trans-fused ring conformations in solution at room temperature.Keywords
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