Regio- and stereochemistry in the intramolecular [4 + 2] and intermolecular [3 + 2] cycloaddition reactions in the synthesis of epoxypyrrolo[3,4-g]indazoles: a density functional theory study

Triple-Dearomative Photocycloaddition: A Strategy to Construct Caged Molecular Frameworks

“…Based on examination of substrate and product structures, the excellent stereoselectivity for reactions affording products such as 14 and 16 may be due to the electrostatic repulsion of the oxygens (shown in red) in substrate 6 (Figure 7) with oxygenated reaction partners such as singlet oxygen and DMAD. 28,29 With optimized conditions in hand, we next explored the substrate scope of heterocyclic reaction partners by using optimized batch or flow conditions (Table 3, vide infra). Furan substrates including 2-substituted and 2,5-disubstituted furans 17 − 20 participated as reaction partners to afford the corresponding caged compounds (not shown), with lower conversions observed upon increasing steric hindrance (entries 1−4).…”