Study on the tandem synthesis of optically active 2-substituted 4 (or 5)-phenyl-1,3-oxazolines

Add time:07/28/2019    Source:sciencedirect.com

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.

We also recommend Trading Suppliers and Manufacturers of (S,S)-2,2'-METHYLENEBIS(4-PHENYL-2-OXAZOLINE) (cas 132098-59-0). Pls Click Website Link as below: cas 132098-59-0 suppliers

Prev:Analytical method for the trace determination of esterified 3- and 2-monochloropropanediol and glycidyl fatty acid esters in various food matrices
Next:Reactions of dimesylthymidine with secondary amines: Easy access to 3′,5′-dideoxy-3′-substituted-5′-alkylaminothymidines - New classes of potential antiviral aminonucleosides.)