Visible-Light-Promoted Tandem Thiol–Ene Click Reaction/Transannular Cyclization and Regioselective Cyclopropane Ring-Opening to Construct Sulfur-Containing <i>Euphorbia</i> Diterpenes

The biorelevant sulfur-containing Euphorbia diterpenes with scarce 5/7/6/3 premyrsinane- and 5/7/6 myrsinane-type backbones were easily constructed from naturally abundant lathyrane-type Euphorbia factor L3 by visible-light-triggered tandem thiol–ene click reaction/transannular cyclization and regioselective cyclopropane ring-opening. The selenide diterpene was also successfully obtained to verify the system universality. This concise synthesis route gives an efficient strategy for obtaining structurally diverse Euphorbia diterpenes under very mild conditions and provides a promising anti-HIV bioactive premyrsinane diterpene 3h.