Control of the photoreactions of carboxylic acid derivatives by use of intermolecular hydrogen bonds

本研究的目的是阐明利用分子间氢键控制羧酸衍生物光反应的适用性。得到的结果如下：1。发现分子间氢键能够控制芳香羧酸衍生物（如酯和亚胺）与烯烃的光环加成的立体选择性。因此，[3+2]- 1,4-萘二甲酸乙酯与甲醇在苯中0℃光环加成时，[3+2]-加合物的立体异构体比例为2.3:1，而[3+2]-光环加成与相应的甲基醚的立体异构体比例为1:1 .3。另一方面，在苯中，[2+2]-甲基-1,8-萘酰亚胺与甲醇在0℃下进行[2+2]-光环加成反应时，[2+2]-加合物的立体异构体的比例为9.0:1，而与相应的甲基醚进行[2+2]-光环加成反应时，立体异构体的比例为2.5:1。此外，分子间氢键控制了光环加成的反应活性和立体选择性。因此，我们考察了醇和羧酸的加入对芳酰亚胺化合物的光性质，特别是发射性质的影响，以阐明控制激发芳酰亚胺化合物的反应性的可能性。结果表明，n -甲基-1,8-萘酰亚胺的荧光强度随着醇类（如2-甲基-1-丙醇）和羧酸类（如乙酸和2,2,2-三氟乙酸）的加入而显著增加，而其他芳香亚胺类化合物（如n -甲基- 1,2和-2,3-萘酰亚胺）的加入则没有这种效果。这种行为的差异可归因于芳香亚胺化合物S_1 （n,π^*）和S_2 （π,π^*）之间的能量差异。

The purpose of this investigation is to clarify the applicability of the control of the photoreactions of carboxylic acid derivatives by use of intermolecular hydrogen bonds.The results obtained are as follows:1. Intermolecular hydrogen bonds were found to be able to control the stereoselectivity of the photocycloadditions of aromatic carboxylic acid derivatives, such as esters and imides, with alkenes. Thus, in the [3+2]-photocycloaddition of dimenthyl 1,4-naphthalenedicarboxylate with methallyl alcohol in benzene at 0 ℃, the ratio of the of the stereoisomers of the [3+2]-adducts was 2.3 : 1, although in the [3+2]-photocycloaddition with the corresponding methyl ether the ratio of the stereoisomers was 1 : 1.3. On the other hand, in the [2+2]-photocycloaddition of N-methyl-1,8-naphthalimide with methallyl alcohol in benzene at 0 ℃, the ratio of the stereoisomers of the [2+2]-adducts was 9.0 : 1, although in the [2+2]-photocycloaddition with the corresponding methyl ether the ratio of the stereoisomers was 2.5 : 1. Furthermore, the intermolecular hydrogen bonds were found to control reactivity of the photocycloadditions as well as the stereoselectivity.2. Thus we examined the effect of the addition of alcohols and carboxylic acids on the photoproperties, especially emission properties, of the aromatic imide compounds to elucidate the possibility of the control of the reactivity of the excited aromatic imide compounds. As the results, the fluorescence intensity of N-methyl-1,8-naphthalimide was found to be remarkably increased by the addition of alcohols, such as 2-methyl-1-propanol, and carboxylic acids, such as acetic acid and 2,2,2-trifluoroacetic acid, while no such effect was observed by use of other aromatic imide compounds, such as N-methyl-1, 2-and -2,3-naphthalimide. The difference of the behavior may be attributed to the energy differences between S_1 (n,π^*) and S_2 (π,π^*) of the aromatic imide compounds.