Dihydrooxazine N-Oxide Intermediates as Resting States in Organocatalytic Kinetic Resolution of Functionalized Nitroallylic Amines with Aldehydes.
Kinetic resolution of nitroallylic amines was established using chiral α,α-l-diphenylprolinol silyl ether auxiliary through isolation of the dihydrooxazine N-oxide intermediates. Further hydrolyzing the resting states provided tetrahydropyridines in high chemical yields and high to excellent stereoselectivities (up to >20:1 dr and 98% ee). A detailed mechanistic explanation for stereoselective protonation in the dihydrooxazine was probed computationally. In addition, the probable intermediates in α-halogenation of aldehydes (masked with enamines) were isolated to provide crystallographic evidence.
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Ramani
R
Gurubrahamam
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Yan Ming
YM
Chen
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Wan-Yun
WY
Huang
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Yu-Te
YT
Chan
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Hsiang-Kai
HK
Chang
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Ming-Kang
MK
Tsai
Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Kwunmin
K
Chen