87443-39-8Relevant articles and documents
Study on the tandem synthesis of optically active 2-substituted 4 (or 5)-phenyl-1,3-oxazolines
Jiang, Haizhen,Lu, Wenjun,Cai, Yeshan,Wan, Wen,Wu, Shaoxiong,Zhu, Shizheng,Hao, Jian
, p. 2150 - 2156 (2013/03/14)
Optically active (S)-2-aryl-4 (or 5)-phenyl-1,3-oxazolines and (S)-2-fluoroalkyl-4-phenyl-1,3-oxazolines were synthesized from a tandem one-pot reaction of (S)-2-amino-2-phenylethanol with a corresponding carboxylic acid in toluene at 90 °C in the presence of PPh3/CBr4 and excess Et3N. The use of aromatic carboxylic acids were determined to proceed through N-(2-bromo-1-phenyl-ethyl)-arylamides 5 and N-aroyl aziridine intermediates 6, which resulted in the formation of (S)-2-aryl-4-phenyl-1,3- oxazolines and (S)-2-aryl-5-phenyl-1,3-oxazolines, respectively. Concurrently, the reaction with fluorinated aliphatic carboxylic acid substrates proceeded via N-(2-hydroxy-1-phenyl-ethyl)-fluoroalkyl amide intermediates 8, which were converted into N-(2-bromo-1-phenyl-ethyl)-fluoroalkyl amide intermediates 9, and then into (S)-2-fluoroalkyl-4-phenyl-1,3-oxazolines as final products. Reaction mechanisms that mainly passed through the formation of aziridine intermediates 6 in the reaction with aromatic carboxylic acids and the formation of fluoroalkyl amide intermediates 8 and 9 in the reaction with fluorinated aliphatic carboxylic acid were proposed. The acidities of the carboxylic acids that were employed were found to play a key role in the selective formation of various intermediates during this reaction.
Catalytic asymmetric hydrogenation of N-Boc-imidazoles and oxazoles
Kuwano, Ryoichi,Kameyama, Nao,Ikeda, Ryuhei
supporting information; experimental part, p. 7312 - 7315 (2011/06/24)
Substituted imidazoles and oxazoles were respectively hydrogenated into the corresponding chiral imidazolines and oxazolines (up to 99% ee). The highly enantioselective hydrogenation was achieved by using the chiral ruthenium catalyst, which is generated
AN ASYMMETRIC SYNTHESIS OF CHIRAL PHTHALIDES VIA CHIRAL LITHIATED OXAZOLINES
Meyers, A. I.,Hanagan, Mary Ann,Trefonas, L. M.,Baker, R. J.
, p. 1991 - 1999 (2007/10/02)
Chiral aromatic oxazolines were prepared for utilization in asymmetric C-C bonding reactions.Lithiation of aryloxazolines could not be accomplished directly but were efficiently lithiated via halogen metal exchange of the o-bromo derivative (16).The resulting lithio compound (9) reacted smoothly with carbonyls to give adducts 19 but with poor stereoselectivity.Hydrolysis gave the phthalides 4 in poor ee's (20-25percent).When the lithio-oxazolines 9 were transformed into 21, they now served as chiral electrophiles.Addition of organometallics to 21 gave, particularly with Grignard reagents, useful levels of asymmetric induction which, after hydrolysis, gave phthalides 4 in 40-80percent ee.
