Cobalt-catalyzed cyclization of N-methoxy benzamides with alkynes using an internal oxidant through C-H/N-O bond activation was written by Sivakumar, Ganesan;Vijeta, Arjun;Jeganmohan, Masilamani. And the article was included in Chemistry – A European Journal in 2016.Reference of 16356-02-8 This article mentions the following:
The cyclization of substituted N-methoxy benzamides with alkynes in the presence of an easily affordable cobalt complex and NaOAc provided isoquinolone derivatives, e.g., I in good to excellent yields. The cyclization reaction was compatible with a range of functional group-substituted benzamides, as well as ester- and alc.-substituted alkynes. The cobalt complex [CoIIICp*(OR)2] (R = Me or Ac) served as an efficient catalyst for the cyclization reaction. Later, isoquinolone derivatives were converted into 1-chloro and 1-bromo substituted isoquinoline derivatives in excellent yields in the presence of POCl3 or PBr3. In the experiment, the researchers used many compounds, for example, 1,4-Dimethoxy-2-butyne (cas: 16356-02-8Reference of 16356-02-8).
1,4-Dimethoxy-2-butyne (cas: 16356-02-8) belongs to ethers. Of all the functional groups, ethers are the least reactive ones. Ether bonds are quite stable towards bases, oxidizing agents and reducing agents. The unique properties of ethers (i.e., that they are strongly polar, with nonbonding electron pairs but no hydroxyl group) enhance the formation and use of many reagents. For example, Grignard reagents cannot form unless an ether is present to share its lone pair of electrons with the magnesium atom. Complexation of the magnesium atom stabilizes the Grignard reagent and helps to keep it in solution.Reference of 16356-02-8
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem