Photocyclization of diarylethenes: the effect of imidazole on the oxidative photodegradation process

Abstract

It was found that imidazole prevents the side process of diarylethenes photocyclization and the photodegradation of photochromic compounds.

Photoinduced Skeletal Rearrangement of Diarylethenes: Photorelease of Lewis Acid and Synthetic Applications

“…We have previously found that amines, including DABCO, facilitate the photorearrangement of DAEs . In this cyclization, the use of DABCO also resulted in a significant increase in the yields of photoproducts 2a and 2b to reach a quantitative value for 2a .…”

“…We have previously found that amines, including DABCO, facilitate the photorearrangement of DAEs. 39 In this cyclization, the use of DABCO also resulted in a significant increase in the yields of photoproducts 2a and 2b to reach a quantitative value for 2a. The high yields are possibly associated with both the facilitation of proton abstraction upon cyclization at an unsubstituted carbon atom and with the reversibility of the process upon photocyclization at a halogensubstituted position (Scheme 3).…”

“…4-(5-Methyl-2-phenyloxazol-4-yl)-3-(thiophen-3-yl)­furan-2­(5 H )-one 1d (0.485 g, 1.5 mmol) and sulfuryl chloride (0.13 mL, 1.65 mmol) were suspended in CH 2 Cl 2 (15 mL). Afterward, the solution was refluxed for 30 min (TLC control), subsequently poured on ice–water (100 mL), and extracted with CH 2 Cl 2 (2 × 20 mL).…”

Photocyclization of Diarylethenes: The Effect of Electron and Proton Acceptors as Additives

“…However, if the reaction is carried out in chloroform in the presence of DABCO, then the radical process is greatly slowed down and after 2 h of irradiation, the yield of 7 is 71% vs 20% for naphthothiophene 8 (entry 12 in Table ). Based on our recent studies , and these results, it can be assumed that DABCO plays a dual role in these processes. The first of them is to facilitate the deprotonation process and the second is to suppress photochemical oxidative processes.…”

Switching the Mallory Reaction to Synthesis of Naphthalenes, Benzannulated Heterocycles, and Their Derivatives

“…In particular, the diarylethene triplet was detected in a study of the photoinduced rearrangement of diarylethene 37c . It was shown that upon irradiation of diarylethenes 37c and 56a the cycloaddition of oxazole substituents with photogenerated singlet oxygen is possible . This undesired process can be bypassed under aerobic conditions by using N- methylpyrrolidone as the solvent or by using amines such as DABCO or imidazole as singlet oxygen quenchers .…”