Effect of an Extra Chloro Substituent on Photochemistry of o-Alkylphenacyl Chloride

Abstract

The title compound, α,α-dichloro-o-methylacetophenone, was prepared and its photochemical behavior was investigated. Addition of an extra chlorine at alpha position to the carbonyl showed many different features from photochemical reactivities of mono chloro analogue, 2,5-dimethylphenacyl chloride. In benzene, a rearrangement product with a formal 1,5-Cl shift and a reduction product were formed beside indanone. In methanol, solvolysis and cyclization of a common dienol intermediate occurred at comparable reaction rates.

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

“…67 Park and collaborators have recently shown that photolysis of 2,4,6-trialkylphenacyl benzoates can also lead to the corresponding benzocyclobutenols (6 in Scheme 5) in addition to indanones, 55 whereas irradiation of α-dichloro-2-acetophenone yields a mixture of various photoproducts. 68 Berkessel and co-workers used the photoenolization reaction as a tool to study the cyclization of 4′-benzophenone-substituted nucleoside derivatives as models for ribonucleotide reductases. 69 Klań and co-workers reported that the photolysis of 2-(alkoxymethyl)-5-methyl-α-chloroacetophenones (13) is very sensitive to traces of water in the solvent (Scheme 9).…”

“…Klán and co-workers showed that photolysis of 4,5-dimethoxy-2-methylphenacyl benzoate can lead to the corresponding indanone derivative that is a precursor for the subsequent synthesis of donepezil, a centrally acting reversible acetylcholinesterase inhibitor used to treat Alzheimer’s disease . Park and collaborators have recently shown that photolysis of 2,4,6-trialkylphenacyl benzoates can also lead to the corresponding benzocyclobutenols ( 6 in Scheme ) in addition to indanones, whereas irradiation of α-dichloro-2-acetophenone yields a mixture of various photoproducts . Berkessel and co-workers used the photoenolization reaction as a tool to study the cyclization of 4′-benzophenone-substituted nucleoside derivatives as models for ribonucleotide reductases …”

Photoenolization-Induced Oxirane Ring Opening in 2,5-Dimethylbenzoyl Oxiranes To Form Pharmaceutically Promising Indanone Derivatives

“…Klán and co-workers showed that photolysis of a 4,5-dimethoxyphenacyl derivative can lead to an indanone precursor for the synthesis of donepezil . Wang and co-workers used this concept in polymer-supported synthesis, and Park and co-workers utilized this reaction in photopolymerization and the synthesis of various indanone and benzocyclobutenol derivatives. , …”