Synthesis of an Isoindoline-Annulated, Tricyclic Sultam Library via Microwave-Assisted, Continuous-Flow Organic Synthesis (MACOS)

Abstract

A microwave-assisted, continuous-flow organic synthesis (MACOS) protocol for the synthesis of an isoindoline-annulated, tricyclic sultam library, utilizing a Heck–aza-Michael (HaM) strategy, is reported. This sequence involves a Heck reaction on vinylsulfonamides with batch microwave heating followed by a one-pot, sequential intramolecular aza-Michael cyclization/Boc-deprotection using MACOS. Subsequent cyclization with either 1,1′-carbonyldiimidazole or chloromethyl pivalate using MACOS provided an array of tricyclic sultams. This efficient three-step protocol requires only a few hours to produce the target sultams starting from simple starting materials. Using this strategy, a 38-member library of isoindoline-annulated sultams was generated in good to excellent overall yields (53–87%).