849361-04-2Relevant academic research and scientific papers
Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide
Nemoto, Tetsuhiro,Harada, Teisuke,Matsumoto, Takayoshi,Hamada, Yasumasa
, p. 6304 - 6307 (2008/02/10)
A Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide is described. Asymmetric allylic substitution using acyclic β-keto esters with a nitrogen functional group at the α-carbon as prochiral nucleophiles proceeded in the presence of 5 mol % of Pd catalyst, 10 mol % of chiral diaminophosphine oxide 1j, BSA, and appropriate additives, affording the corresponding quaternary α-amino acid derivatives in excellent yield and in up to 92% ee.
Ti-Crossed-Claisen condensation between carboxylic esters and acid chlorides or acids: A highly selective and general method for the preparation of various β-keto esters
Misaki, Tomonori,Nagase, Ryohei,Matsumoto, Kunshi,Tanabe, Yoo
, p. 2854 - 2855 (2007/10/03)
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 β-keto esters in good yields with excellent selectivities (19 examples, ～48-95% yield; cross/self-selectivity = ～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, ～70-92% yield; cross/self-selectivity = ～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. Copyright
