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Influences of alpha-substituent in 4,5-dimethoxy-2-nitrobenzyl-protected esters on both photocleavage rate and subsequent photoreaction of the generated 2-nitrosophenyl ketones: A novel photorearrangement of 2-nitrosophenyl ketones

Paper ID Volume ID Publish Year Pages File Format Full-Text
26251 43943 2016 7 PDF Available
Title
Influences of alpha-substituent in 4,5-dimethoxy-2-nitrobenzyl-protected esters on both photocleavage rate and subsequent photoreaction of the generated 2-nitrosophenyl ketones: A novel photorearrangement of 2-nitrosophenyl ketones
Abstract

•Alpha-substituted 2-nitrobenzyl esters form multiple by-products upon photodeprotection.•2-Nitrosoketones isolated after deprotection reaction formed similar photoproducts.•Isopropyl substitution gave bicyclic oxazole as a major photorearrangement product.•Tertiary-butyl substitution gave azoxy and azo compounds as photoirradiation products.•Nature of α-substituent affects photodeprotection rate and types of photo-products.

Ultraviolet(UV)-induced photodeprotection of 2-nitrobenzyl esters to release the acid with formation of the corresponding 2-nitrosoketone proceeds rapidly when the α-position in the 2-nitrobenzyl group is substituted by a branched alkyl group. The generated 2-nitrosophenyl ketones undergo multiple photoreactions, including a unique photorearrangement, depending upon the nature of the α-substituent. 2-Nitrosoketone bearing an isopropyl substituent mainly undergoes this rearrangement to afford a bicyclic oxazole via a shift of the isopropyl group to the bridgehead position, resulting in loss of aromaticity of the six-membered ring. 2-Nitrosopheyl ketone bearing a tertiary-butyl substituent gives mainly azoxy and azo compounds via intermolecular reaction of nitrosoketones with loss of isobutene. The photorearrangement does not proceed in the case of the phenyl-substituted compound. These findings will be helpful for the selection and/or design of photolabile protecting groups.

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Keywords
Alpha-substitutent; 2-Nitrobenzyl; Esters; 2-Nitrosoarene; Branched-acyl-group; Photorearrangment
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Influences of alpha-substituent in 4,5-dimethoxy-2-nitrobenzyl-protected esters on both photocleavage rate and subsequent photoreaction of the generated 2-nitrosophenyl ketones: A novel photorearrangement of 2-nitrosophenyl ketones
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 321, 1 May 2016, Pages 41–47
Authors
, , , , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us