Three-Component Tandem-Intramolecular Hydroamination Reactions in One Pot Involving Indoles, 2-Aminobenzyl Alcohols, and 2-Alkynylbenzaldehydes: Consecutive 7-<i>endo</i>-<i>trig</i>and Electrophilic 6-<i>endo</i>-<i>dig</i>Cyclizations
作者:Srinivas Samala、Mohammad Saifuddin、Anil K. Mandadapu、Bijoy Kundu
DOI:10.1002/ejoc.201300100
日期:2013.6
A one-pot protocol for the synthesis of indole-based annulated polyheterocycles involvingconsecutive 7-endo-trig and electrophilic 6-endo-dig cyclizations is described. The reaction proceeds initially through annulation of 5-methoxyindole, 2-amino benzyl alcohol and 2-alkynylbenzaldehyde
A Sequential One-Pot Protocol for the Synthesis of Dihydrobenzo[6,7]indolo-[3′,4′:3,4,5]azepino[2,1-a]isoquinolines Using a Gold-Silver Combined Catalyst
A sequential one-pot protocol for the synthesis of indole-based peri-annulated polyheterocycles using trifluoroacetic acid and a gold-silver combined catalyst system is described. The reaction is thought to proceed via an imine formation-cationic pi-cyclization-alkyne activation-intramolecular hydroamination sequence to yield novel dihydrobenzo[6,7]indolo[3',4':3,4,5]azepino[2,1-a]isoquinolines in good yields.
Synthesis of Triazolo Isoquinolines and Isochromenes from 2-Alkynylbenzaldehyde via Domino Reactions under Transition-Metal-Free Conditions
作者:Rajesh K. Arigela、Srinivas Samala、Rohit Mahar、Sanjeev K. Shukla、Bijoy Kundu
DOI:10.1021/jo401929q
日期:2013.10.18
We describe two simple straightforward syntheses of triazolo isoquinolines (3) and isochromenes (7) from 2-alkynylbenzaldehydes (1) as a common synthon. The synthetic strategy for 3 involves formation of the (E)-1-(2-nitrovinyl)-2-(alkynyl)benzene species 2 via condensation of synthon 1 with nitromethane followed by a [3 + 2] cycloaddition/extrusion of the nitro group/regioselective 6-endo cyclization domino sequence. In yet another strategy, the synthon 1 was condensed with nitromethane followed by electrophilic iodo cyclization of the resulting 2-nitro-1-(2-(alkynyl)phenyl)ethanol (6) to furnish iodo isochromene derivatives. The salient feature of the above two strategies involves formation of the corresponding heterocycles under metal-free conditions in good yields.