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[摘要]：A new, solvent-free tetrabutylammonium-hydrogensulfate-catalysed one-pot procedure to synthesise angular benzopyran-annulated pyrazoles, all of which incorporate a tertiary ring-junction carbon, has been demonstrated. A typical intermediate Knoevenagel heterodiene, formed by the reaction of 2-(alkenyloxy)- or 2-(alkynyloxy)acetophenones with pyrazolones smoothly underwent a subsequent hetero-DielsAlder reaction to give chromeno-fused pyrazoles in a highly stereoselective reaction. When nitro-containing DKHDA products were treated further with Fe/HCl in tandem, they formed the corresponding amino frameworks in a reduction step, which highlights a new possibility for this cascade route to give aminopolyheterocycles. The stereochemistry of all new tertiary ring-junction carbon-containing polyheterocycles was confirmed by 2D NMR spectroscopy experiments, DQF-COSY and NOESY, and single crystal X-ray diffraction data. None of the products has had their biological profiled evaluated before, and they are expected to have heterosteroidal biological functions. |
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