Regioselective Cyclization of (Indol-3-yl)pentyn-3-ols as an Approach to (Tetrahydro)carbazoles.

An acid-catalyzed, highly regioselective cycloisomerization as well as dehydro-cyclization of (indol-3-yl)pentyn-3-ols has been reported for the selective synthesis of tetrahydrocarbazoles and carbazoles. This process is mild and found to be very general in terms of structural diversity of substrates. Utilizing the strategy, an efficient synthetic approach for the functionalized frameworks of carbazomycins A-D has also been developed.