Synthesis of triazolo isoquinolines and isochromenes from 2-alkynylbenzaldehyde via domino reactions under transition-metal-free conditions.
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.
Medicinal and Process Chemistry Division and ‡Sophisticated Analytical Instrumental Facility, CSIR-Central Drug Research Institute , Lucknow 226001, India.
Rajesh K
RK
Arigela
Srinivas
S
Samala
Rohit
R
Mahar
Sanjeev K
SK
Shukla
Bijoy
B
Kundu
D001547:Benzaldehydes / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D002384:Catalysis; D007546:Isoquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry
D001547:Benzaldehydes; D001578:Benzopyrans; D007546:Isoquinolines; D028561:Transition Elements; D014230:Triazoles