The regioselective lithiation of dithienothiazines followed by electrophilic trapping in a one-pot fashion is an efficient route to 2-mono- and 2,6-difunctionalized dithienothiazines. A pseudo five-component dilithiation–diformylation–double-Wittig olefination sequence gives a dithienothiazine symmetrically functionalized with α,β-unsaturated ester side chains in excellent yield.
Key words
addition reactions - heterocycles - lithiation - multicomponent reactions - Wittig reactions