Design of high-performance catalysts based on acid-base combined salts and development of highly selective reactions

The design of highly functionalized artificial catalysts is very important for practical organic synthesis. We have succeeded in the rational design of high-performance catalysts based on acid-base combined salts. Acid-base combined salt catalysts can be classified into three types: (1) Metal oxide-Lewis base combined salts, (2) Brønsted acid-Brønsted base combined salts, and (3) Lewis acid-Lewis base combined salts. Here we report our recent studies on development of highly selective cyclization reactions for the synthesis of key intermediates of bioactive natural products. Molybdenum (VI) oxide-bis(quinolinolato) complexes (class 1) efficiently catalyze biomimetic dehydrative cyclization of serine, threonine and cysteine derivatives to give oxazolines and thiazolines. Chiral 1,1′-binaphthyl-2,2′-diammonium salts (class 2) are useful catalysts for enantioselective Diels-Alder reaction of α-acyloxyacroleins. We also have developed the first enantioselective biomimetic iodocyclization of isoprenoids using a chiral nucleophilic promoter (class 3). acid-base combined salt, dehydrative cyclization, molybdenum (VI) oxide, oxazoline, Diels-Alder reaction,.