In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called Gold(I)-Catalyzed Synthesis of Tetrahydrocarbazoles via Cascade [3,3]-Propargylic Rearrangement/[4+2] Cycloaddition of Vinylindoles and Propargylic Esters, published in 2016, which mentions a compound: 21778-81-4, Name is 5-Methoxy-1H-indole-2-carbaldehyde, Molecular C10H9NO2, Quality Control of 5-Methoxy-1H-indole-2-carbaldehyde.
A gold(I)-catalyzed cascade [3,3]-propargylic rearrangement and [4+2] cycloaddition reaction of 2-vinylindoles, e.g., I, with propargylic esters R3CH(OZ)(C=CR4) (R3 = CH3, C6H5, 4-FC6H4, etc.; R4 = H, Et, n-Pr, i-Pr, Ph; Z = pivaloyl, acetyl) has been reported. The reaction leads to the synthesis of highly substituted tetrahydrocarbazole derivatives, e.g., II, in high yields and diastereoselectivities. Furthermore, a preliminary screening for an asym. version of this reaction has been described.
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Reference:
Pyridazine – Wikipedia,
Pyridazine | C4H4N2 – PubChem