A General Method to Diverse Cinnolines and Cinnolinium Salts was written by Zhao, Dongbing;Wu, Qian;Huang, Xiaolei;Song, Feijie;Lv, Taiyong;You, Jingsong. And the article was included in Chemistry – A European Journal in 2013.Quality Control of 1,4-Dimethoxy-2-butyne This article mentions the following:
Cinnolines and cinnolinium salts represent pharmaceutically and biol. important structures with anticancer, antimicrobial, antiinflammatory, antiparasitic, trypanocidal, and foliar herbicide activities as well as structural motifs with optical and luminescent characteristics. In this work, a highly efficient and general method to create both cinnoline and cinnolinium frameworks through the rhodium(III)-catalyzed oxidative C-H activation/cyclization of azo compounds with alkynes has been developed which exhibits an unprecedented capacity to install versatile functional groups at various positions of the cinnoline ring. The catalytic protocol could be also extended to synthesize polycyclic cinnolinium salts, e.g., I (X-rays single crystal structure shown), through twice ortho-directed C-H activation and cyclization. In the experiment, the researchers used many compounds, for example, 1,4-Dimethoxy-2-butyne (cas: 16356-02-8Quality Control of 1,4-Dimethoxy-2-butyne).
1,4-Dimethoxy-2-butyne (cas: 16356-02-8) belongs to ethers. Ether is less polar than esters, alcohols or amines because of the oxygen atom that is unable to participate in hydrogen bonding due to the presence of bulky alkyl groups on both sides of the oxygen atom. Electron-deficient reagents are also stabilized by ethers. For example, borane (BH3) is a useful reagent for making alcohols. Pure borane exists as its dimer, diborane (B2H6), a toxic gas that is inconvenient and hazardous to use. Borane forms stable complexes with ethers, however, and it is often supplied and used as its liquid complex with tetrahydrofuran (THF).Quality Control of 1,4-Dimethoxy-2-butyne
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem