2003 Imidazole derivatives

Imidazole derivativesR 0190 Synthesis of Substituted 1H-Imidazol-1-ylmethylpiperidines. Facile Separation of

1,4- and 1,5-Disubstituted Imidazoles. — Starting with optically active ethyl nipeco-tate (I), the N-substituted and 1,2-disubstituted imidazoles (V) are synthesized by direct alkylation of the tosylate derived from (III). Analogous reaction with 4(5)-methylimi-dazole (VI) does not proceed regioselectively, but affords a mixture of 1,4- and 1,5-re-gioisomers (VII) and (VIII). These can be separated efficiently using triphenylmethyl chloride, which coordinates selectively to the 1,5-disubstituted imidazole (VIII). This procedure is applied to the synthesis of various 1,4-disubstituted imidazoles, e.g. (XI). — (RIVERA, J.; JAYASURIYA, N.; RANE, D.; KEERTIKAR, K.; FERREIRA, J. A.; CHAO, J.; MINOR, K.; GUZI*, T.; Tetrahedron Lett. 43 (2002) 49, 8917-8919; Dep. Chem. Res., Schering-Plough Res. Inst., Kenilworth, NJ 07033, USA; Eng.) — Roy

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