The initial results on a novel procedure for the synthesis of benzo[b]carbazols via gold(I)catalyzed tandem cyclization/Migration/cyclization is described. The procedure allowed the access to a highly functionalized benzo[b]carbazols in a one-pot process starting from tertiary anilines. The mechanism of this reaction by using gold(I) catalysis, interestingly proceeded via 5-endo-dig cyclization with successively migration of benzyl substituent on 2 and 3 position of indole, leading to the formation of benzyl substituted indole derivatives. We are proposing a cyclodimerization and aromatization via 6-exo-dig with the help of gold(I)-carbene. Initial optimization with Tertiary Aniline 4, 5mol% of (Acetonitrile)[(2-biphenyl)di-tert-butylphosphine]gold(I) hexafluoroantimonate as Gold(I)-catalyst, Dry-DCM or Dry-DCE at 23 °C. But unfortunately, we do not get result. Then we rise the temp of reaction in Dry-DCE upto 60 °C with 10mol% of gold(I) catalyst and then we get substituted indole as a cyclized product with 95% yield which is confirmed by H 1 , C 13 and NOE spectrum. Overall, we get first intermolecular cyclized product of benzyl substituted indole with excellent yield.
The initial results on a novel procedure for the synthesis of pyrrolo[1,2-a]indoles via gold(I)-catalyzed tandem cyclization/C-H activation/cyclization is described. The procedure allowed the access to a highly functionalized pyrrolo[1,2-a]indoles in a one-pot process starting from anilinodiynes. The mechanism of this reaction by using gold(I) catalysis, interestingly proceeded via 5-endo-dig cyclization at only one of the alkyne of the diyne fragment, leadig to the formation of 2-alkynylindole derivative. We are purposing a Csp 3 -H bond activation and generating gold(I)carbene species with [1,5]-H migration and cyclization following by [1,2]-H shift. The result we achieved 1-benzhydryl-2-(phenylethynyl)-1-H-indole moiety first cyclization was confirmed by using 1 H, 13 C NMR spectroscopy and X-ray. Interestingly we have developed intramolecular cyclization of indole moiety with high yield, short reaction time and room temperature.
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