Poly(ethylene glycol)-Supported 4-Alkylthio-Substituted Aniline − a Useful Starting Material for the Soluble Polymer-Supported Synthesis of Imines and 1,2,3,4-Tetrahydroquinolines
✍ Scribed by Rita Annunziata; Maurizio Benaglia; Mauro Cinquini; Franco Cozzi
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 279 KB
- Volume
- 2002
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
A 4-alkylthio-substituted aniline anchored to a modified poly(ethylene glycol) of M w = 5000 was selected as a convenient starting material for the liquid-phase synthesis of various imines. Some of these imines were employed in a three-component synthesis of 1,2,3,4-tetrahydroquinolines, carried out in the presence of 2-methylpropanal, different nucleophiles, and catalytic amounts of Yb(OTf) 3 . Four-com-
Results and Discussion
On the basis of our experience in the PEG-supported synthesis of imines and β-lactams, [10] mesylate 1, obtained in three steps and 95% overall yield from the monomethyl ether of PEG with M w ϭ 5000 (MeOPEG), was selected as Ϫ to a stirred 0.1 solution of amine 2 (1.0Ϫ2.0 g, ca. 0.2Ϫ0.4 mmol) in dry MeOH, and the mixture was stirred either at room temp. for 96 h or at reflux for 24 h. When benzyl alcohol was the nucleophile, DCM was used as reaction solvent and 3 molequiv. of nucleophile were employed. The reaction was then worked up as described before to afford the crude product.