Ag(I)-Promoted, Diastereoselective Cyclo-isomerization of N-Alkynyl-7-azaindole-2-carbinols. Selective Synthesis of syn-1,2-Diarylpyrrolo[1,2-a]indol-3-ones and (Z)-8-Benzylideneoxazolo[3',4'':1,5]pyrrolo[2,3-b]pyridines.

ABSTRACT

The design and development of an Ag(I)-promoted, highly diastereoselective cycloisomerization strategy for the synthesis of syn-1,2-diarylpyrrolo[1,2-a]indol-3-ones from N-alkynyl-indole-2-carbinols is reported. The H218O control experiment and identification of 18O-labeled product suggested the involvement of an external water. The 7-azaindole substrates showned a distinct reactivity to give the (Z)-8-benzylideneoxazolo[3',4'1,5]pyrrolo[2,3-b]pyridines. Key features of this strategy are its 100% atom economy, access to important heterocycles, diverse substrate scope, yields up to 95%, operationally simple procedure, and distinct reactivity of indole vs 7-azaindoles.