Synthesis of 8‑Alkoxy‑5H‑isochromeno[3,4‑c]isoquinolines and 1‑Alkoxy-4-arylisoquinolin-3-ols through Rh(III)-Catalyzed C–H Functionalization of Benzimidates with 4‑Diazoisochroman-3-imines and 4‑Diazoisoquinolin-3-ones

Rh­(III)-catalyzed C–H activation/annulation of benzimidates with 4-diazoisochroman-3-imines furnished 8-alkoxy-5H-isochromeno­[3,4-c]­isoquinolines in moderate to excellent yields with a broad range of substrate scope. The reaction was carried out under mild reaction conditions and could be scaled up with practical usage. Similar reaction between benzimidates and 4-diazoisoquinolin-3-ones provided 1-alkoxy-4-arylisoquinolin-3-ols in excellent yields. Moreover, the synthesized products could be conveniently transformed to the corresponding heterocycles with a 1,8-naphthyridinone or isochromenopyridinone core, which are privileged structures in medicinal chemistry.以铑(III)（Rh(III)）催化的苯甲亚胺酸酯（benzimidates）与4-重氮异色满-3-亚胺（4-diazoisochroman-3-imines）的C-H活化/环化反应，可生成8-烷氧基-5H-异色烯并[3,4-c]异喹啉类化合物，产率中等至优异，且底物适用范围广泛。该反应在温和条件下进行，可放大制备，具备实用价值。苯甲亚胺酸酯与4-重氮异喹啉-3-酮（4-diazoisoquinolin-3-ones）的同类反应则可获得优异产率的1-烷氧基-4-芳基异喹啉-3-醇（1-alkoxy-4-arylisoquinolin-3-ols）。此外，所合成的产物可便捷地转化为含有1,8-萘啶酮（1,8-naphthyridinone）或异色烯并吡啶酮（isochromenopyridinone）母核的相应杂环化合物，这类结构是药物化学中的优势骨架。