Science of Synthesis

Grimmett, M. R., Science of Synthesis, (2002) 12, 599.

Unsaturated carbon groups in which the multiple bond is potentially conjugated with the hetero ring do not react like normal alkenes and alkynes. Electrophilic addition reactions are difficult and may not follow the usual alkene pathways. Treatment of 1-alkenylbenzimidazoles with bromine followed by reaction with triethylamine gives only the product of substitution of the β-hydrogen by bromine.[‌471‌] The vinyl function of 1-vinyl-1,3-dihydro-2H-benzimidazole-2-thione (‌113‌) can be reduced by catalytic hydrogenation methods. Ionic catalysts promote normal electrophilic addition giving ‌114‌, while radical initiators lead to anti-Markovnikov addition of thiols to form ‌115‌ (‌Scheme 56‌).[‌472‌] Oxidation with reagents such as peroxide tend to induce polymerization, but some oxidative procedures give the carboxylic acid.

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References

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• 8.Meeeee-Meee, (8888) M 88e8, 888.
• 8.Meeeee-Meee, (8888) M 88-8, 8888.
• 8.Meeeee-Meee, (8888) M 8e, 888.