Chemo-, Regio- and Stereoselective Heck Arylation of Allylated Malonates: Mechanistic Insights by ESI-MS and Synthetic Application toward 5-Arylmethyl-γ-lactones

We describe herein a general method for the controlled Heck arylation of allylated malonates. Both electron-rich and electron-poor aryldiazonium salts were readily employed as the aryl-transfer agents in good yields and in high chemo-, regio-, and stereoselectivity without formation of decarboxylated byproducts. Reaction monitoring via ESI-MS was used to support the formation of chelated Pd species through the catalytic cycle. Additionally, some Heck adducts were successfully used in the total synthesis of pharmacologically active γ-lactones.