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PREPARATION AND REACTIONS OF 3-(AMINOMETHYLENE)-3H-INDOLES
Moriya, Tamon,Hagio, Katsuaki,Yoneda, Naoto
, p. 1711 - 1721 (2007/10/02)
A series of 3-(aminomethylene)-3H-indoles (1a-e and 6a-8a) was prepared by the condensation of 3-indolecarbaldehydes (2-5) with secondary amines.Among them, 3-(1-pyrrolidinylmethylene)-3H-indoles (1a and 6a-8a) were obtained as stable colorless prisms, while 3-(piperidinomethylene)-3H-indole (1b) and 3-(morpholinomethylene)-3H-indole (1c) readily polymerized in refluxing benzene.Reaction of 1 with electrophiles, such as alkyl and acyl halides, gave 1-substituted 3-aminomethylene-3H-indolium salts, which were converted to the corresponding 1-substituted 3-indolecarbaldehydes by hydrolysis.Reaction of 1 with active methylene compounds proceeded under mild reaction conditions to afford the corresponding condensation products in good yields.Successive reaction of 1 with electrophiles and nucleophiles provided a convenient route to 1,3-disubstituted indole derivatives.Keywords-conjugated enamine; 3-indolecarbaldehyde; 3-(aminomethylene)-3H-indole; 3-(aminomethylene)-3H-indolium salt; active methylene compounds; 3-(substituted vinyl)indole; gramine; electrophilic reaction; condensation
