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Part-A Studies on 2-methyl indoline derivatives…..
the heterocyclic ring to give indolines, but conversions were affected by
indole-indoline equilibrium.
The regioselective hydroamination and cyclization of aliphatic and
aromatic amino olefins in the presence of (LaHL2)2 (L = η5pentamethylcyclopentadienyl)
96 and borontrifluoride using diethylether and
the divalent samarium complexes Cp2'Sm and Cp2'Sm (THF)2 (Cp' = η5-
97
Me5C5) and to give 2-methyl indoline was reported. Thus,
CH2=CH(CH2)3NH2 was treated with a catalytic amount of (LaHL2)2 in a
hydrocarbon solvent (toluene, cyclohexane or pentane) to give 2-methyl
indoline. Kinetic and mechanistic evidence presented that the turnoverlimiting
step is intramolecular olefin insertion into the La-N bond followed by
rapid protonolysis of the resulting La-C bond.
Lawin et. al. 98 reported the preparation of 2-methyl indoline from 2methyl
indole through electrolytic reduction.
Meyers and Melot 99 carried out N-alkylation on indoline followed by
methylation at C2 position in the presence of t-butyllithium and dealkylation
using hydrazinehydrate resulted into corresponding indoline.
Yadav et. al. 100 reported that N-allyl anilines underwent 3-aza-Cope
rearrangement in the presence of Zn +2 montmorillonite under microwave
irradiation in the absence of solvent to afford indoline derivatives in high
yields. Similarly aryl allyl thioethers were rearranged to
dihydrobenzothiophenes.
Jimenez et. al. 101 reported mixtures of products, while 2-allyl aniline
underwent reduction through beta-cyclodextrin medium.
N-methyl-2-methyl indoline was synthesized from N-methyl-2-methyl
indole using tin and concentrated hydrochloric acid, 102 indium and ammonium
chloride, 103 and from t-butyl 2-methyl-1H-indole-1-carboxylate using rhodium
phosphine complex, 104 PhTRAP-ruthenium catalyst, 105 and palladium and
polymethylhydrosiloxane. 106
Department of Chemistry, Saurashtra University, Rajkot – 360 005 18