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

点击翻译按钮获取中文摘要

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.