Diversity‐Oriented Synthesis of Novel 2′‐Aminospiro[11 H ‐indeno[1,2‐ b ]quinoxaline‐11,4′‐[4 H ]pyran] Derivatives via a One‐Pot Four‐Component Reaction

A sequential one‐pot four‐component reaction for the efficient synthesis of novel 2′‐aminospiro[11 H ‐indeno[1,2‐ b ]quinoxaline‐11,4′‐[4 H ]pyran] derivatives 5 in the presence of AcONH 4 as a neutral, inexpensive, and dually activating catalyst is described ( Scheme 1 ). The syntheses are achieved by reacting ninhydrin ( 1 ) with benzene‐1,2‐diamines 2 to give indenoquinoxalines, which are trapped in situ by malono derivatives 2 and various α ‐methylenecarbonyl compounds 4 through cyclization, providing the multifunctionalized 2′‐aminospiro[11 H ‐indeno[1,2‐ b ]quinoxaline‐11,4′‐[4 H ]pyran] analogs 5 . This chemistry provides an efficient and promising synthetic way of proceeding for the diversity‐oriented construction of the spiro[indenoquinoxalino‐pyran] skeleton.