Diastereoselective Synthesis of Rauhut–Currier-Type Adducts via an Unexpected α‑Addition of α,β-Unsaturated γ‑Butyrolactams to Coumarin Derivatives
journal contributionposted on 01.12.2016, 00:00 by Shu-Mei Yang, Ganapuram Madhusudhan Reddy, Meng-Hsien Liu, Tzu-Ping Wang, Jhen-Kuei Yu, Wenwei Lin
A novel, base-catalyzed and highly diastereoselective direct Michael addition-isomerization sequence is presented for the efficient synthesis of Rauhut–Currier-type adducts. An unexpected α-addition of γ-butyrolactam onto the 3-acyl coumarin derivatives was observed rather than the γ-addition, which is more common. The adducts could further undergo hydrolysis/decarboxylation to generate the products which are equivalent to those obtained by α-addition of γ-butyrolactam onto the corresponding chalcones.