Dye-sensitized photooxygenation of tert-butylpyrroles

Abstract

The isomeric 1,2 and 3-mono-tert-butylpyrroles were photooxygenated in methanol and acetone solvents using Rose Bengal and Methylene Blue singlet oxygen sensitizers. Their rates of photooxygenation are comparable to that of 2,5-dimethylfuran in methanol, but slower in acetone. Fifteen different photooxygenation products from both methanol and acetone solvents have been isolated, and their structures have been determined by spectroscopic methods. They include the expected 5-methoxy-and 5-hydroxylactams, 3-hydroxylactams, imides, pivalamide, and an unusual yellow keto lactam. The intermediate endo peroxides have been prepared at -78°and identified by low-temperature NMR.

Real‐time Selective Detection of Hydrogen Peroxide Based on a Tantalum Deposited Pencil Lead Electrode for Evaluation of Enzyme Activities

“…We deposited Ta on pencil lead at À1.6 V to reduce Ta precursor, according to our previous report, by potentiostatic method for 30 min. It is notable that a single broad cathodic peak was observed with pencil lead unlike previous reports [34,[41][42][43].…”

The Oxidation of Pyrrole

“…In 1975, Lightner and Pak published a detailed investigation into the oxidation of various tert ‐butyl‐substituted pyrroles with singlet oxygen . As with previous oxidations of pyrrole with singlet oxygen, various product mixtures were observed, with pyrrolinones ( 24 and 25 ) and maleimides ( 26 ) being the major compounds obtained (Scheme ).…”

Reactions of pyrrole, imidazole, and pyrazole with ozone: kinetics and mechanisms

“…59 Additionally, earlier studies which investigated the oxidation of substituted pyrroles with singlet oxygen suggested both C2,C3-and C2,C5-cycloadditions. [60][61][62] These studies found the product with two oxygen atoms added to the C2,C5-positions (equivalent to TP2) and the ring-opened product (equivalent to TP1). Compounds containing a maleimide, formamide, or an epoxide moiety were also identified or hypothesized as minor products.…”