ANOMERIC-LIKE SUBSTITUENT EFFECTS ON THE CHAIR CHAIR CONFORMATIONAL EQUILIBRIUM OF THE 2-OXO-1,3,2-OXAZAPHOSPHORINANE RING-SYSTEM

被引:28
作者
BENTRUDE, WG
SETZER, WN
KHAN, M
SOPCHIK, AE
RAMLI, E
机构
[1] Department of Chemistry, University of Utah, Salt Lake City
[2] Department of Chemistry, University of Alabama Huntsville, Huntsville
关键词
D O I
10.1021/jo00021a031
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The chair-chair equilibria for a series of 5,5-dimethyl-2-oxo-(2-p-X-anilino)-1,3,2-oxazaphosphorinanes were determined by H-1 NMR. The percentage of chair conformer with the p-X-anilino group axial is increased by the presence of electron withdrawing X, while the opposite is true for electron-donor para X. Reasonably good linear plots of log K vs sigma-p were obtained in the solvents acetone-d6, CD3CN, and CD3NO2 with rho = 0.28-0.36. These results are interpreted in terms of the dominance of the endo anomeric effect involving overlap of the endocyclic N(3) and O(1) p lone pairs with the axial P-N sigma* orbital (p-XC6H4NHP).
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页码:6127 / 6131
页数:5
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