Synthesis of fused tetracyclic spiroindoles via palladium-catalysed cascade cyclisation

摘要

Efficient palladium-catalysed cascade cydisation to form spiroindoles is developed. Treatment of indoles bearing a propargyl chloride side chain at the 3-position with various external nucleophiles in the presence of a catalytic amount of Pd_2(dba)_3 CHCl_3/dppb and Cs_2CO_3 in THF gives fused tetracyclic spiroindoles in moderate to good yields.