Preparation of quinolines from resin-bound esters using titanium reagents |
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Authors: | Calum Macleod Dieter W Hamprecht |
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Institution: | a Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK b GlaxoSmithKline, Centro Ricerche, Via Fleming 4, 37135 Verona, Italy |
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Abstract: | ortho-Amino homobenzylic thioacetals are prepared from ortho-nitrobenzaldehydes via homologation using an alpha-methoxy Wittig reagent. Titanium reagents are generated from the 1,3-dithianes using a low valent titanium reagent and are then used to alkylidenate resin-bound esters. An N-silylated Boc group protects the ortho-amino functionality. Traceless SPS of quinolines is completed by treating the resulting resin-bound enol ethers with TFA and then oxidizing with manganese dioxide to give 2-substituted quinolines in high purity without the need for chromatography. |
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Keywords: | Quinolines Titanium and compounds Solid-phase synthesis Thioacetals Wittig reaction |
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