TY - JOUR
T1 - Oxazoline-oxazinone oxidative rearrangement. Divergent syntheses of (2S,3S)-4,4,4-trifluorovaline and (2S,4S)-5,5,5-trifluoroleucine
AU - Pigza, Julie A.
AU - Quach, Tim
AU - Molinski, Tadeusz F.
PY - 2009/8/7
Y1 - 2009/8/7
N2 - (Chemical Equation Presented) Stereoselective syntheses of the valuable fluorinated amino acids (2S,3S)-4,4,4-trifluorovaline and (2S,4S)-5,5,5- trifluoroleucine have been achieved starting from 4,4,4-trifluoro-3- methylbutanoic acid by using a conceptually simple transformation: conversion to a chiral oxazoline, SeO2-promoted oxidative rearrangement to the dihydro-2H-oxazinone, and face-selective hydrogenation of the C=N bond, followed by hydrogenolysis-hydrolysis. The transformation is limited by the tendency of the intermediate β-trifluoromethyldihydrooxazinone to undergo imine-enamine isomerization. Both amino acids were obtained as configurationally pure hydrochloride salts identical in all respects with those in literature reports.
AB - (Chemical Equation Presented) Stereoselective syntheses of the valuable fluorinated amino acids (2S,3S)-4,4,4-trifluorovaline and (2S,4S)-5,5,5- trifluoroleucine have been achieved starting from 4,4,4-trifluoro-3- methylbutanoic acid by using a conceptually simple transformation: conversion to a chiral oxazoline, SeO2-promoted oxidative rearrangement to the dihydro-2H-oxazinone, and face-selective hydrogenation of the C=N bond, followed by hydrogenolysis-hydrolysis. The transformation is limited by the tendency of the intermediate β-trifluoromethyldihydrooxazinone to undergo imine-enamine isomerization. Both amino acids were obtained as configurationally pure hydrochloride salts identical in all respects with those in literature reports.
UR - http://www.scopus.com/inward/record.url?scp=68049142866&partnerID=8YFLogxK
U2 - 10.1021/jo900654y
DO - 10.1021/jo900654y
M3 - Article
C2 - 19537688
AN - SCOPUS:68049142866
SN - 0022-3263
VL - 74
SP - 5510
EP - 5515
JO - The Journal of Organic Chemistry
JF - The Journal of Organic Chemistry
IS - 15
ER -