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Abstract
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A sequential one-pot four-component reaction for the efficient synthesis of novel 2′-aminospiro[11H-indeno[1,2-b]quinoxaline-11,4′-[4H]pyran] derivatives 5 in the presence of AcONH4 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[11H-indeno[1,2-b]quinoxaline-11,4′-[4H]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.
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