Asymmetric synthesis of [2,3-(13)C(2),(15)N]-4-benzyloxy-5,6-diphenyl-2,3,5,6-tetrahydro-4H-oxazine-2-one via lipase TL-mediated kinetic resolution of benzoin: general procedure for the synthesis of [2,3-(13)C(2),(15)N]-L-alanine.
Lipase TL-mediated kinetic resolution of benzoin proceeded to give the corresponding optically pure (R)-benzoin (R)-1. On the other hand, (S)-benzoin O-acetate (S)-7 could be hydrolyzed without epimerization to give (S)-benzoin (S)-1 under alkaline conditions. Furthermore, both enantiomers of benzoin (1) were converted to [(15)N]-(1R,2S)- and (1S,2R)- 2-amino-1,2-diphenylethanol (3a and 3b), respectively, according to the procedure reported previously. [2,3-(13)C(2),(15)N]-(5S,6R)-4-benzyloxy-5,6-diphenyl-2,3,5,6-tetrahydro-4H-oxazine-2-one (10) was synthesized from ethyl [1,2-(13)C(2)]bromoacetate and (1R,2S)-2-amino-1,2-diphenylethanol (3b) in three steps. Finally, [2,3-(13)C(2),(15)N]-L-alanine (12) was prepared via alkylation of the lactone 10 and hydrogenation of the alkylated product 11.
Aoyagi
Y
Y
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA. aoyagiy@ps.toyaku.ac.jp
Iijima
A
A
Williams
R M
RM
D000409:Alanine / Q000138:chemical synthesis*; D001573:Benzoin / Q000737:chemistry; D002250:Carbon Radioisotopes; D007553:Isotope Labeling / Q000379:methods*; D008049:Lipase / Q000494:pharmacology; D009587:Nitrogen Isotopes; D010078:Oxazines / Q000737:chemistry; D013237:Stereoisomerism
D002250:Carbon Radioisotopes; D009587:Nitrogen Isotopes; D010078:Oxazines; D008049:Lipase; D001573:Benzoin; D000409:Alanine