Redox Cyclization of Amides and Sulfonamides with Nitrous Oxide for Direct Synthesis of Heterocycles was written by Lai, Zhencheng;Wang, Chaorong;Li, Jiaming;Cui, Sunliang. And the article was included in Organic Letters in 2020.Electric Literature of C9H13NO2S This article mentions the following:
A redox cyclization of amides R1C(O)NHR2 (R1 = C6H5, 1-naphthyl, 5-methylthiophen-2-yl, etc.; R2 = Me, t-Bu, cyclopropyl, etc.) and sulfonamides 4-R3C6H4S(O)2NHR4 (R3 = H, Me, t-Bu, Ph, OMe, Cl; R4 = Me, t-Bu, cyclopropyl, etc.) with nitrous oxide (N2O) for the direct synthesis of heterocycles, e.g., I has been described. Various amides and sulfonamides could undergo directed ortho metalation (DoM) by treatment with BuLi, and the lithium intermediate could be trapped by N2O gas to achieve redox cyclization. N2O serves as an N-atom donor to mediate the intramol. coupling of lithium species toward heterocycle formation with free external oxidant. This protocol offers a direct synthesis of heterocycles with features of readily available starting materials, simple operation, and a broad substrate scope. In the experiment, the researchers used many compounds, for example, N-Isopropylbenzenesulfonamide (cas: 5339-69-5Electric Literature of C9H13NO2S).
N-Isopropylbenzenesulfonamide (cas: 5339-69-5) belongs to amides. Amides are pervasive in nature and technology. Proteins and important plastics like Nylons, Aramid, Twaron, and Kevlar are polymers whose units are connected by amide groups (polyamides); these linkages are easily formed, confer structural rigidity, and resist hydrolysis. Amides can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent.Electric Literature of C9H13NO2S
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics