BF₃-Etherate-Promoted Cascade Reaction of 2-Alkynylanilines with Nitriles: One-Pot Assembly of 4-Amido-Cinnolines

Abstract

A BF3-etherate-promoted cascade reaction of nitriles with 2-alkynylanilines is described. This method achieves the formation of two new C-N bonds through a reaction sequence of diazotization with t-BuONO, nucleophilic addition of the alkyne to the BF3-coordinated diazonium ion, followed by nitrile addition to the intermediary vinyl cation and hydrolysis. The method provides efficient and general access to a variety of 4-amido-cinnolines. Notable features of the method include its broad functional group tolerance and avoidance of transition metals.

Recent Advances in the Synthesis of Nitrogen Heterocycles Using Arenediazonium Salts as Nitrogen Sources

“…[27] The diazonium intermediates which were generated from 2- . [28] This reaction proceeds smoothly at room temperature to construct two new CÀ N bonds in a single reaction, and provides a mild and practical synthetic pathway to access diverse 4-amido-cinnolines in moderate to good yields. Notable features of the method include mild reaction conditions, excellent functional group tolerance, and avoidance of transition metals.…”

tert‐Butyl Nitrite (TBN), a Multitasking Reagent in Organic Synthesis

“…The remarkable features are transition‐metal free, wide functional group tolerance, mild condition, and moderate to good reaction yields together with the incorporation of an amide functionality. This method continues via a reaction sequence of diazotization, followed by a nucleophilic addition of the alkyne to the diazonium ion to generate vinyl cation, nitrile addition to the intermediary vinyl cation and finally hydrolysis resulting in the incorporation of two new C−N bonds (Scheme ) …”

“…The remarkablef eatures are transition-metal free, wide functional group tolerance, mild condition, and moderate to good reaction yields together with the incorporation of an amide functionality.T his method continues via ar eaction sequence of diazotization, followed by a nucleophilic addition of the alkyne to the diazonium ion to generate vinyl cation, nitrile addition to the intermediary vinyl cation and finally hydrolysis resultingi nt he incorporation of two new CÀNb onds (Scheme 110). [136] In 2017, Wang group developed aP d-catalyzedm ethod for the synthesis of indazole 2-oxides from o-aryl anilinesu sing TBN as aN Os ource. The important feature of this protocol is the dual role of TBN as aN Os ource as well as an oxidant, as a result, there is no requirement of additional reagent.A nother advantage of this protocol is that it covers ab road range of substrate scope giving moderate to good yields.…”

C−H Mono‐Nitration of Indolines using tert‐Butyl Nitrite

“…In last few decades tert ‐butyl nitrite (TBN) has emerged as a versatile organic reagent and have shown huge applications in numerous organic transformations like diazotization, nitrosation, oximation, oxidation, etc. This metal‐free reagent is also an excellent nitrating agent which adopt mild reaction condition.…”