Synthesis of 6a,6b,13,13a-tetrahydro-6H-5-oxa-12a-azadibenzo[a,g]fluorene derivatives via cycloaddition reactions of isoquinolinium salts with 3-nitrochromenes.

An efficient and diastereoselective synthetic procedure for functionalized 6a,6b,13,13a-tetrahydro-6H-5-oxa-12a-azadibenzo[a,g]fluorene derivatives was successfully developed by the cycloaddition reaction of isoquinolinium salts and 3-nitrochromenes with triethylamine as base in ethanol at room temperature. 1H NMR data and single crystal structures confirm the production and isolation of a single stereoisomer.