4 research outputs found
Lewis Acid Mediated Cascade Friedel–Craft/Alkyne Indol-2-yl Cation Cyclization/Vinyl Cation Trapping for the Synthesis of <i>N</i>‑Fused Indole Derivatives
A Lewis acid promoted cascade Friedel-Craft/alkyne
indol-2-yl cation
cyclization/vinyl cation trapping for an efficient and divergent synthesis
of <i>N</i>-fused indoles is developed. The present study
illustrates the first example of an alkyne as a nucleophile on the
less explored indol-2-yl cation. The method efficiently affords pharmaceutically
important pyrrolizino-quinolines and complex fused indole derivatives
in high yields
Cascade Radical Cyclization of <i>N</i>‑Propargylindoles: Substituents Dictate Stereoselective Formation of <i>N</i>‑Fused Indolines versus Indoles
An efficient protocol for the synthesis
of pyrrolo[1,2-<i>a</i>]indole derivatives having sulfide
functionality using
cascade radical cyclization on propargylindole is described. The nature
of the substituents at the propargylic carbon bearing nitrogen of
the indole has a profound effect on the rate, yield, and nature of
the product obtained by the cascade radical cyclization. An expeditious
one-pot route for cascade radical cyclization–desulfurization
is also presented. Products obtained were elaborated to the core of
the putative structure of the yuremamine and indoline derivative with
five contiguous stereocenters
Counter-Ion-Dependent Alkyne Iminium Ion Cyclization for Divergent Synthesis of <i>N</i>‑Fused Indolylidine, Indole, and Indoline Derivatives Promoted by the Lewis/Bronsted Acid
Divergent
synthesis of <i>N</i>-fused indolylidine, indole,
and indoline derivatives using alkyne iminium ion cyclization is described.
Trapping of vinyl cation intermediate generated after alkyne iminium
ion cyclization was found to be dependent on the Lewis/Bronsted acid
and solvent used. <i>N</i>-Fused indolylidine triflate could
be used in the divergent synthesis of <i>N</i>-fused indole
derivatives
Lewis Acid Promoted Oxonium Ion Driven Carboamination of Alkynes for the Synthesis of 4‑Alkoxy Quinolines
Lewis acid mediated
multisegment coupling cascade is designed for
the synthesis of densely substituted 4-alkoxy quinolines via an oxonium
ion triggered alkyne carboamination sequence involving C–C
and C–N bond formations. Cyclic ether fused-quinolines could
also be accessed using this fast, operationally simple, high yielding,
chemoselective and functional group tolerant method. Versatility and
utility of this methodology is demonstrated by postfunctionalization
of products obtained and its use in synthesis of potent drug molecules