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

本研究旨在阐明利用分子间氢键控制羧酸衍生物的光反应的适用性，得到的结果如下：1.分子间氢键能够控制芳香族羧酸衍生物与烯烃的光环加成反应的立体选择性。因此，在[3+2]-光环加成反应中，1，4-萘二甲酸二甲酯与甲基烯丙醇在苯中的[3+2]-光环加成反应中，[3+2]-加合物的立体异构体比例为2.3：1，而在与相应的甲醚的[3+2]-光环加成反应中，立体异构体的比例为1：1.3。另一方面，在N-甲基-1，8-萘亚胺与甲基烯丙醇在苯中的[2+2]-光环加成反应中，在0℃时，[2+2]-加合物的立体异构体比例为9.0：1，而在与相应的甲醚的[2+2]-光环加成反应中，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反应的活性和立体选择性。因此，我们考察了醇和羧酸的添加对芳香族酰亚胺化合物的光学性质，特别是发射性质的影响，以阐明控制激发态芳香族酰亚胺化合物反应性的可能性。结果表明，N-甲基-1，8-萘酰亚胺的荧光强度随醇类化合物(如2-甲基-1-丙醇)和羧酸类化合物(如冰醋酸、2，2，2-三氟乙酸)的加入而显著增强，而对其他芳香族酰亚胺化合物如N-甲基-1，2-和-2，3-萘酰亚胺则无明显影响。这种行为的差异可能归因于芳香族酰亚胺化合物的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.