Bartoli G, Bartolacci M, Bosco M, Foglia G, Giuliani A, Marcantoni E, Sambri L, Torregiani E. The Michael addition of indoles to alpha,beta-unsaturated ketones catalyzed by CeCl3.7H2O-NaI combination supported on silica gel.
J Org Chem 2003;
68:4594-7. [PMID:
12762781 DOI:
10.1021/jo034303y]
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Abstract
Alkylation of indoles by means of the Michael addition has been the subject of a number of investigation. It is well established that regioselectivity in the additions of indoles to electron-deficient alkenes is strongly controlled by the reaction medium. In a continuation of the work on developing greener and cleaner technologies, the cerium(III) chloride heptahydrate and sodium iodide combination supported on silica gel catalyzes the alkylation of various indoles with alpha,beta-unsaturated ketones giving 3-(3-oxoalkyl)indole derivatives in good yields. The substitution on the indole nucleus occurred exclusively at the 3-position, and N-alkylation products have not been observed.
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