Formation of substituted truxillic and truxinic acids in plant cell walls—a rationale
作者:A.B. Hanley、W.R. Russell、A. Chesson
DOI:10.1016/0031-9422(93)85004-b
日期:1993.7
Abstract The formation of phenolic cyclobutane dicarboxylic acids (truxillic and truxinic acids) in plant cell wall materials was investigated using model compounds. Two possible mechanisms were considered—cyclodimerization initiated by light or by a free radical process. Diesters formed by reaction of cinnamic acid with a series of diols had a range of distances separating the double bonds and, upon
Lewis acid catalysis of photochemical reactions. 4. Selective isomerization of cinnamic esters
作者:Frederick D. Lewis、Joe D. Oxman、Lester L. Gibson、Hilary L. Hampsch、Suzanne L. Quillen
DOI:10.1021/ja00271a033
日期:1986.5
upon complexation. Enhanced E ..-->.. Z photoisomerization upon complex formation is a consequence of selective excitation of the E vs. Z complex, more efficient isomerization of the excited E vs. Z complex, and larger equilibrium constants for complexation of E vs. Z esters. The photoequilibria obtained for bis cinnamic esters are highly enriched in the Z,Z and Z,E isomers in accord with independent
已经研究了几种 (E)- 和 (Z)- 肉桂酸酯、双肉桂酸酯以及模型酯和内酯在路易斯酸存在和不存在下的光谱性质和光异构化反应。使用路易斯酸如 BF/sub 3/ 或 EtAlCl/sub 2/ 可提高光异构化效率,并使光平衡向热力学不太稳定的 Z 异构体移动。增强的 E ..-->.. Z 光异构化是由基态酯-路易斯酸复合物的选择性激发引起的。这些配合物已通过 /sup 1/H NMR、紫外和荧光光谱表征。络合的平衡常数取决于酯的电子给体强度及其构象迁移率。这些因素也决定了在络合时观察到的电子吸收光谱中红移的幅度。复合物形成时增强的 E ..--> .. Z 光异构化是 E 与 Z 复合物选择性激发、激发的 E 与 Z 复合物更有效的异构化以及 E 与 Z 复合物络合的更大平衡常数的结果。 Z酯。根据两个肉桂酸酯基团的独立异构化,双肉桂酸酯获得的光平衡高度富含 Z,Z 和 Z,E 异构体;然而,在
Concerning methoxy substituent effect and topotactic assistance by methylene chain on photocyclization of n-methylene dicinnamates
Methoxy substituent effect and topotactic assistance by the methylene chain of n-methylene dicinnamates upon the photocyclization to the cyclobutane derivatives was explored and the relative efficiencies were rationalized in terms of the odd electron densities of S1 state obtained by the CNDO/S-CI excited state calculation.
Improved Cs<sub>2</sub>CO<sub>3</sub>Promoted O-Alkylation of Acids
作者:Jay P. Parrish、Eric E. Dueno、Seok-In Kim、Kyung Woon Jung
DOI:10.1080/00397910008086893
日期:2000.8
Cesium carbonate mediated O-alkylation of carboxylic acids was efficiently carried out under mild in situ conditions to give the corresponding esters exclusively. Chiral templates including alpha-hydroxy and alpha-alkoxy acids were also converted to their corresponding esters with no observed racemization.
Mikhant'eva, O. N.; Romanova, V. S.; Mikhant'ev, V. B., Journal of applied chemistry of the USSR, 1981, vol. 54, # 5, p. 990 - 993
作者:Mikhant'eva, O. N.、Romanova, V. S.、Mikhant'ev, V. B.