The acid-induced nucleophilic addition of a nitrile to a carbenium ion, followed by hydrolysis to the corresponding amide.
Mechanism of the Ritter Reaction
Any substrate capable of generating a stable carbenium ion is a suitable starting material; primary alcohols do not react under these conditions, with exception of benzylic alcohols:
The carbenium ion adds to the nitrile nitrogen to give a nitrilium ion intermediate, which undergoes hydrolysis to the corresponding amide upon aqueous work-up.
A direct difunctionalization protocol of alkenes with nitriles and thiols under metal-free synthesis conditions provides various β-acetamido sulfides with very good yields simply by using inexpensive molecular iodine as a catalyst, DMSO as a mild oxidant, and readily available thiols as thiolating reagents.
H. Cui, X. Liu, W. Wei, D. Yang, C. He, T. Zhang, H. Wang, J. Org. Chem., 2016, 81, 2252-2260.
A transition-metal-free, direct, and efficient acetamidosulphenylation reaction of alkenes using nitriles as the nucleophiles offers a broad substrate scope and high regioselectivity and provides straightforward access to acetamidosulfide derivatives in good yields via a radical process.
Y. Zheng, Y. He, G. Rong, X. Zhang, Y. Wang, K. Dong, X. Xu, J. Mao, Org. Lett., 2015, 17, 5444-5447.
In a direct and efficient method for the acetamidosulfenylation reaction of alkenes, NaI was used as a catalyst, DMSO as the oxidant, nitriles as both the solvent and nucleophiles and stable, readily available Bunte salts as thiolating reagents. The reactions were carried out under mild conditions to provide β-acetamido sulfides in good yields. Moreover, the reaction can be performed with alcohols as nucleophiles.
R. Zhang, Z. Yan, D. Wang, Y. Wang, S. Lin, Synlett, 2017, 28, 1195-1200.