Synthesis of Enantiomerically Pure α-Substituted Propargylic Amines by Reaction of Organoaluminum Reagents with Oxazolidines
摘要:
Various oxazolidines prepared in two steps from (R)-phenylglycinol react at 0 degrees C with dialkyl-alkynylalane-triethylamine complexes in the presence of trimethylaluminum in high yield and diastereoselectivity. Enantiomerically pure primary alpha-substituted propargylamines cah be easily obtained in two steps after removal of ferrocenylmethyl protective group under smooth acidic conditions and oxidative cleavage of the chiral appendage.
Synthesis of Enantiomerically Pure α-Substituted Propargylic Amines by Reaction of Organoaluminum Reagents with Oxazolidines
摘要:
Various oxazolidines prepared in two steps from (R)-phenylglycinol react at 0 degrees C with dialkyl-alkynylalane-triethylamine complexes in the presence of trimethylaluminum in high yield and diastereoselectivity. Enantiomerically pure primary alpha-substituted propargylamines cah be easily obtained in two steps after removal of ferrocenylmethyl protective group under smooth acidic conditions and oxidative cleavage of the chiral appendage.
Chiral oxazolidines obtained by condensation of aldehydes with (-).(R)- or (+).(S)-N-benzylphenylglycinol react with the Reformatsky reagent derived from ethylbromoacetate, in mild reaction conditions (Et2O or CH2Cl2, 0°C, 15-60 min), leading to ethyl β-amino carboxylates in moderate to good diastereomeric excess (60-92%). These ring opening products are transformed into primary β-aminoesters, in
A new efficient and scalable route to chiral non-racemic α-substituted propargylamines is described. The reaction pathway consists of the diastereoselective addition of mixed alkynylaluminum reagents to oxazolidines derived from R-(−)-phenylglycinol.