Highly-Efficient Conversion of Primary Amides to Nitriles Using Indium(III) Triflate as the Catalyst

Abstract

Indium(III) triflate, a trivalent indium reagent, was shown to be a highly-efficient catalyst for the conversion of primary amides to the corresponding nitriles. The successful reactions required 5 mol% of indium(III) triflate, and toluene was proved to be the most suitable solvent. Various amides were subjected to this method, and each produced the corresponding nitriles in excellent yields.

Dehydrosulfurization of Aromatic Thioamides to Nitriles Using Indium(III) Triflate

“…Using 3-methyl thiobenzamide as the starting substrate, a search for the optimal conditions of dehydrosulfurization was attempted, as presented in Table 1. The amount of N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) was fixed at 3.5 equivalents, as established in our previous report (Figure 1) [24], and thus the catalytic amount of indium(III) triflate and appropriate solvents were investigated. The entries using toluene as the solvent afforded the expected products ( Table 1, entries 1 and 2), whereas the entries using THF ended with no reactions ( Table 1, entries 3 and 4).…”

“…Various aromatic thiobenzamides were subjected to dehydrosulfurization reactions. As shown in Table 2, the reactions proceeded smoothly to give the corresponding nitriles in good to excellent yields [24]. The alkyl group substituents,such as methyl on the aromatic ring and the tert-butyl groups were inert under the reaction conditions of dehydrosulfurization, and gave high yields ( Table 2, entries 1, 3, and 5) [25] [26].…”

“…Ogura et al has reported for the dehydrosulfurization of thioamides to nitriles by using selenium-based and tellurium-based reagents [11]- [15], while Enthaler et al has reported using iron-based and zinc-based reagents [16] [17]. We have studied the catalytic utility of indium reagents, and reported the chemical application of indium reagents, including an efficient conversion of primary amides to nitriles using catalytic indium(III) triflate [18]- [24]. In ongoing research, we have found that the catalytic use of indium(III) triflate facilitates the dehydrosulfurization of thioamides to nitriles.…”

Metal‐Catalyzed Dehydration of Primary Amides to Nitriles

“…An efficient MSTFA dehydration method was also reported by Mineno and coworker using indium(II) triflate (5 mol%, Scheme ) . The reaction requires 3.5 equivalents of MSTFA at refluxing toluene.…”

Chloramine-T-Mediated Oxidation of Benzylic Alcohols Using Indium(III) Triflate

“…We have studied the catalyst effect of indium reagents for past several years, and have reported various chemical transformations using them. [12][13][14][15] Also, there exists a precedent study of selective oxidation of primary alcohols that results only the corresponding aldehyde compounds without the indication of over-oxidation to the carboxylic acids. The study must be a suitable evidence for the compatibility of chloramine-T and transition metal catalyst.…”