posted on 2017-03-17, 00:00authored byQiao Yan, Emma Gin, Martin G. Banwell, Anthony C. Willis, Paul D. Carr
A cross-coupling/reductive
cyclization protocol has been employed
in a unified approach to all four carbolines. So, for example, the
2-nitropyridine 8, which is readily prepared through
an efficient palladium-catalyzed Ullmann cross-coupling reaction,
is reductively cyclized under conventional conditions to give 6,7,8,9-tetrahydro-α-carboline
that is itself readily aromatized to give α-carboline (1).