Enhanced Efficiency and Regioselectivity of Intramolecular (2π + 2π) Photocycloaddition of 1-Cyanonaphthalene Derivative Using Microreactors

Abstract

The intramolecular photocycloaddition of a 1-cyanonaphthalene derivative in microreactors made of poly(dimethylsiloxane) (PDMS) was examined. By using the microreactors and flow system, both the efficiency and regioselectivity increased compared with those under batch conditions.

Flow photochemistry: Old light through new windows

“…Mizuno et al reported the reaction shown in Scheme 2 using a Xe lamp (λ > 290 nm) in a poly(dimethylsiloxane) reactor [25]. The microreactor was compared with a batch reactor and was found to give slightly better selectivity (59:9 versus 56:17) for 4,5-fused system 5 over a 4,6-fused system 6 .…”

“…The microreactor was compared with a batch reactor and was found to give slightly better selectivity (59:9 versus 56:17) for 4,5-fused system 5 over a 4,6-fused system 6 . However, conversion in the microflow system was lower than that in the batch reactor [25]. This was later shown to be due to the reversibility of the cycloaddition to yield 5 , whilst the reaction to yield 6 is irreversible.…”

Micro Reactors, Flow Reactors and Continuous Flow Synthesis

“…The fact that glass micro reactors are transparent is ideal for investigating photochemical processes. Mizuno and co-workers, 25 reported an enhancement in reaction efficiency, as well as regioselectivity, by conducting the photocycloaddition of a naphthalene derivative 32 (Scheme 11) in a transparent micro reactor. The authors found that in batch, irradiation of a 1-cyanonaphthalene derivative 32, using a filtered Xenon lamp (λ > 290 nm), afforded photocycloadducts 33 and 34 in 56% and 17% yield respectively.…”

Preparation of Pentacyclo‐[8.2.1.14,702,903,8] ‐tetradecane‐5,6,11,12‐tetracarboxylic Dianhydride Combined with Gaussian Calculation

“…The ideal light source should be monochromatic light, which can greatly simplify the determination of absolute light intensity. [12][13][14] In addition, the reaction system is turbid due to the insolubility of dianhydride insolvent, and the reaction rate is low for the poor transmittance and uneven illumination. In recent years, it is reported that cyclobutane tetracarboxylic dianhydride was prepared by continuous flow method, which increased the reaction rate and product yield.…”