The chemistry of coumarin derivatives. Part 9. Biaryl hydroxy aldehydes as intermediates in the metal-assisted atropo-enantioselective reduction of biaryl lactones: Structures and aldehyde-lactol equilibria

被引:25
作者
Bringmann, G
Breuning, M
Endress, H
Vitt, D
Peters, K
Peters, EM
机构
[1] Univ Wurzburg, Inst Organ Chem, D-97074 Wurzburg, Germany
[2] Max Planck Inst Festkorperforsch, D-70506 Stuttgart, Germany
关键词
D O I
10.1016/S0040-4020(98)00618-8
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The synthesis of substituted 1-(2'-hydroxyphenyl)naphthalene-2-carbaldehydes 4 and 6-alkoxy-6H-pyrans 7 and 8, analogs of the postulated metallated intermediates in the atropo-enantioselective ring cleavage of configuratively unstable biaryl lactones 2, is described. While the equilibria between the open hydroxy aldehydes 4 and the cyclic lactol structures 3 are completely shifted towards 4 for the derivatives 4c-g with substituents ortho to the biaryl axis, the lactol forms are the dominating structures (ca. 50-100%) for the ortho-unsubstituted compounds. For the lactols 3 and their acetalic analogs 6, 7, and 8, those diastereomeric conformations are preferred (77-100%) that have the exo-oxygen function axial. (C) 1998 Elsevier Science Ltd. All rights reserved.
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页码:10677 / 10690
页数:14
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