Synthesis of 4H-chromenes by an unexpected, K3PO4-mediated intramolecular Rauhut-Currier type reaction.
In an attempt to develop the umpolung of Michael acceptors using chalcones having an enoate moiety under N-heterocyclic carbene (NHC) catalysis, a K3PO4-mediated intramolecular Rauhut-Currier type reaction was observed. This C(sp(2))-C(sp(2)) coupling reaction afforded the biologically important 4H-chromenes in moderate to good yields. It is likely that the enol ether functionality acts as the nucleophilic trigger in this reaction.
Organic Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr Homi Bhabha Road, Pune-411008, India. at.biju@ncl.res.in.
Anup
A
Bhunia
Santhivardhana Reddy
SR
Yetra
Rajesh G
RG
Gonnade
Akkattu T
AT
Biju