Synthesis of highly substituted γ-hydroxybutenolides through the annulation of keto acids with alkynes and subsequent hydroxyl transposition

Abstract

An efficient synthesis of highly functionalized γ-hydroxybutenolides through BF3-catalyzed annulation of keto acids with alkynes is described. Many advantages such as the use of routine reagents, easy operation, and a 100% atom efficiency are demonstrated in the method. The reaction can be readily scaled up to gram quantities, offering good practicality.

Tandem Chemoselective 1,2‐/1,4‐Migration of the Thio Group in Keto Thioesters: An Efficient Approach to Substituted Butenolides

“…(e), Scheme ] under standard conditions also confirmed that 1,4‐migration of the thio group proceeds in a stepwise mechanism. Furthermore, to confirm whether 1,4‐sulfur migration product 3a was generated via 1,2‐sulfur migration product 2a followed by rearrangement, 2a was treated with BF 3 ⋅OEt 2 under optimized reaction conditions [Eq. (f), Scheme ].…”

Elusive Thiyl Radical Migration in a Visible Light Induced Chemoselective Rearrangement of γ‐Keto Acrylate Thioesters: Synthesis of Substituted Butenolides

“…To confirm whether 4a was formed via 1cc by an allylic migration of the sulfur substituent, 1cc was treated under the standard conditions (Eq. d) . However, only the starting materials were recovered.…”

Pd‐Catalyzed Synthesis of γ‐Keto Esters as Key Intermediates for the Synthesis of γ‐Hydroxybutenolides

“…Due to the plethora of biological activities, several synthetic approaches of trisubstituted γ‐hydroxybutenolides were established either via an Indium mediated Barbier‐type reaction with subsequent lactonization/aerobic oxidation, intramolecular oxo ‐Pauson Khand reaction or BF 3 ‐catalyzed intermolecular annulation (Scheme ).…”