DBU-Catalyzed Inter- and Intramolecular Double Michael Addition of Donor–Acceptor Chromone-Pyrazolone/Benzofuranone Synthons: Access to Spiro-Pyrazolone/Benzofuranone-Hexahydroxanthone Hybrids.

A DBU-catalyzed inter- and intramolecular double Michael addition of donor–acceptor chromone-pyrazolone/benzofuranone synthons and 3-methyl-4-nitro-5-alkenylisoxazoles has been established, which constructed structurally diverse spiro-pyrazolone/benzofuranone-hexahydroxanthone hybrids bearing five consecutive stereocenters in good yields (up to 91%) with high diastereoselectivities (up to >20:1 dr). Moreover, this strategy further expanded the synthetic potential of bifunctional donor–acceptor chromones, and demonstrated great potential for applications in medicinal chemistry. [ABSTRACT FROM AUTHOR]