Synthesis of 1,3,3-trimethyl-2-methyleneindolines was written by Nagaraja, S. N.;Sunthankar, S. V.. And the article was included in Journal of Scientific & Industrial Research in 1958.Reference of 4583-55-5 This article mentions the following:
A series of 1,3,3-trimethyl-2-methyleneindolines was prepared by condensation of the substituted phenylhydrazines (I) with MeEtCO in EtOH to give the corresponding phenylhydrazones (II), cyclization of II with 2N H2SO4 to the corresponding 2,3-dimethylindoles (III), and methylation of III with MeI in MeOH to indoline iodides (IV). I were prepared in 40-50% yield by diazotization of the corresponding p-substituted-arylamines and reduction with acidic SnCl2. II were prepared by addition of MeEtCO to I in EtOH, refluxing 1 hr., and distilling in vacuo; p-ClC6H4NHN:CMeEt b0.6-0.7 125-30闂? yield 80%; Br derivative b0.9 120-5闂? yield 73%. To the II, 10 parts by volume 2N H2SO4 was added, the mixture heated 0.5-1 hr. at 95闂? the solution cooled, and the III filtered off. The following 5-substituted III were prepared (5-substituent, % yield, and m.p. given): Cl, 80, 144-5闂? Br, 88, 142-3闂? OMe, 70, 109-10闂? OEt, 65, 114-15闂? NO2, 60-5, 187-8闂?(prepared by nitration of III with KNO3 and concentrated H2SO4 at 3闂?; NH2, 55, 173-4闂?(prepared by reduction of the 5-NO2 derivative of III with alkali and hydrosulfite). III 1, MeOH 10, and MeI 3 parts were heated in an autoclave 4-5 hrs. at 100-10闂? the solution cooled, the solvent evaporated, the residue extracted with boiling H2O, the H2O distilled in vacuo, giving 5-substituted IV. The following IV, isolated and characterized as methiodides, were prepared (5-substituent, % yield, and m.p. of methiodide given): Cl, 60, 221-2闂? OMe, 65, 221-2闂? OEt, 55, 203-4闂? NO2, 62, 203-4闂? NH2, 58, 190-1闂? In the experiment, the researchers used many compounds, for example, 5-Bromo-2,3-dimethyl-1H-indole (cas: 4583-55-5Reference of 4583-55-5).
5-Bromo-2,3-dimethyl-1H-indole (cas: 4583-55-5) belongs to indole derivatives. The indole subunit is an almost ubiquitous component of biologically active natural products, and its study has been the focus of research for decades. In addition to indole, the strain-release chemistry worked for numerous substrates including amines, alcohols, thiols, carboxylic acids, imidazoles, and pyrazoles.Reference of 4583-55-5
Referemce:
Indole alkaloid derivatives as building blocks of natural products from闂佽壈浜崹淇沜illus thuringiensis闂佽壈浜粋鍧闂佽壈浜崹淇沜illus velezensis闂佽壈浜粋鍧 their antibacterial and antifungal activity study,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles