Ti-crossed-Claisen condensation between carboxylic esters and acid chlorides or acids: a highly selective and general method for the preparation of various beta-keto esters.
Ti-crossed-Claisen condensation between a 1:1 mixture of carboxylic esters and acid chlorides promoted by TiCl4-Bu3N-N-methylimidazole proceeded successfully to give various beta-keto esters in good yields with excellent selectivities (19 examples, approximately 48-95% yield; cross/self-selectivity = approximately 96/4-99/1). The present method was extended to the condensation between a 1:1 mixture of carboxylic acids and carboxylic esters (six examples, approximately 70-92% yield; cross/self-selectivity = approximately 91/9-99/1). To demonstrate the utility of the present two Ti-crossed-Claisen condensations, we performed a couple of efficient short-step syntheses of two natural, representative, and useful perfumes, cis-jasmone and (R)-muscone.
Misaki
Tomonori
T
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan.
Nagase
Ryohei
R
Matsumoto
Kunshi
K
Tanabe
Yoo
Y
D002264:Carboxylic Acids / Q000737:chemistry*; D003516:Cycloparaffins / Q000138:chemical synthesis; D003517:Cyclopentanes / Q000138:chemical synthesis; D004952:Esters / Q000138:chemical synthesis / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis*; D054883:Oxylipins
D002264:Carboxylic Acids; D003516:Cycloparaffins; D003517:Cyclopentanes; D004952:Esters; D007659:Ketones; D054883:Oxylipins; C086299:jasmone; C031021:muscone