Roy D, Tharra P, Baire B. An approach to functionalized carbazoles from
Z-enoate propargylic alcohols. A unified total synthesis of
N-Me-carazostatin,
N-Me-carbazoquinocin C and
N-Me-lipocarbazole A4.
Chem Commun (Camb) 2022;
58:10210-10213. [PMID:
36000534 DOI:
10.1039/d2cc03526j]
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Abstract
Development of an acid catalyzed, intramolecular benzannulation of indoles for the synthesis of functionalized carbazoles has been reported. The indole appended Z-enoate propargylic alcohols have been employed. The N-EDG-indoles involve the 5-exo-dig cyclization followed by 1,2-migration to give the carbazole-butenoates, whereas the N-EWG-indoles undergo the Z-enoate assisted Meyer-Schuster rearrangement to give the dihydrocarbazole-4-oxo-butanoates. Utilizing one of the 2-methyl-carbazole-butyraldehyde (obtained from the corresponding carbazole-butanoate) as the key intermediate, we have developed a simple approach for an efficient synthesis of N-Me-carazostatin, N-Me-carbazoquinocin C and N-Me-lipocarbazole A4.
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