149030-63-7Relevant academic research and scientific papers
Asymmetric Synthesis of Optically Active Phthalides via ortho-Lithiation and Cyclization of Chiral N-Monosubstituted Benzamides
Matsui, Syuichi,Uejima, Akinori,Suzuki, Yoshinori,Tanaka, Kazuhiko
, p. 701 - 704 (2007/10/02)
The chiral N-monosubstituted benzamides 1a-d, derived from (S)-(-)-α-phenylethylamine and L--(-)-phenylalanine, gave the ortho-lithiated species on treatment with butyllithium (2.2 equiv.) and TMEDA in THF at 0 deg C.The resulting lithio amides reacted smoothly with aldehydes to afford the expected ortho substituted products 2a-d as diastereoisomeric mixzures, which were converted quantitatively into the phthalides 3a, b on acidic hydrolysis.Use of (S)-(-)-N-benzoyl-O-methylphenylalaninol 1c and (S)-(-)-N-(3-methoxybenzoyl)-O-methylphenylalaninol 1d as the amide resulted in consistently high diastereoselectivities.The reaction of the dianions derived from 1c with valeraldehyde gave, after cyclization, (S)-(-)-3-butylphthalide, an essential oil of celery, with 83 percent e.e.
