Short and efficient route toward α-substituted N-arylazetidines from acetanilides via Mitsunobu reaction

Diboronic Acid Anhydrides as Effective Catalysts for the Hydroxy-Directed Dehydrative Amidation of Carboxylic Acids

The direct catalytic dehydrative amidation of β-hydroxycarboxylic acids with amines is described. A biphenyl-based diboronic acid anhydride with a B-O-B skeleton is shown to be an exceptionally effective catalyst for the reaction, providing β-hydroxycarboxylic amides in high to excellent yields with a low catalyst loading (minimum of 0.01 mol %, TON up to 7,500). This hydroxy-directed amidation shows excellent chemoselectivity and is applicable to gram-scale drug synthesis.

Synthesis of Exclusively 4-Substituted β-Lactams through the Kinugasa Reaction Utilizing Calcium Carbide

A new Kinugasa reaction protocol has been elaborated for the one-pot synthesis of 4-substituted β-lactams utilizing calcium carbide and nitrone derivatives. Calcium carbide is thereby activated by TBAF·3H₂O in the presence of CuCl/NMI. The ease of synthesis and use of inexpensive chemicals provides rapid access of practical quantities of β-lactams exclusively substituted at position 4.

Lewis Acid and (Hypo)iodite Relay Catalysis Allows a Strategy for the Synthesis of Polysubstituted Azetidines and Tetrahydroquinolines

A catalytic [3 + 1]-annulation reaction between cyclopropane 1,1-diester and aromatic amine is developed based on the relay catalysis strategy. Lewis acid-catalyzed nucleophilic ring opening of cyclopropane 1,1-diester with aromatic amine and (hypo)iodite-catalyzed C-N bond formation are combined successfully in one reaction. Using this reaction, biologically important azetidines and tetrahydroquinolines can be prepared directly.