Divergent synthesis of medium-sized rings with controllable ring sizes represents a longstanding challenge in organic synthesis. Herein, we developed a transition-metal-catalyzed switchable divergent cycloaddition of para-quinone methides and vinylethylene carbonates by controlling the steric hindrance of substituent. Different from reported alkoxide-triggered annulations, this process undergoes a regiodivergent allylation of para-quinone methides followed by 1, 6-addition reaction, providing a new route to selectively synthesize seven- to ten-membered nitrogen-containing heterocycles in high yields with excellent regioselectivities. This protocol features a broad substrate scope, wide functional group tolerance as well as operational simplicity. The reaction mechanism was investigated by conducting a series of control experiments as well as DFT calculations and the origins of the regioselectivities of the cycloaddition process were rationalized.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |