Modification of (1R,2S)-1,2-diphenyl-2-aminoethanol for the highly enantioselective, asymmetric alkylation of N-diphenylphosphinoyl arylimines with dialkylzinc.
Experimental studies on the modification of (1R,2S)-1,2-diphenyl-2-aminoethanol, which is used to promote the alkylation of N-diphenylphosphinoyl benzalimine with diethylzinc, revealed that N-monosubstituted amino alcohols exhibited higher enantioselectivities than their N,N-disubstituted counterparts and imino alcohols. Application of the optimal chiral ligand 3c to activate the reaction of N-diphenylphosphinoyl arylimines with diethylzinc and dibutylzinc resulted in excellent enantiomeric selectivities of up to 98% ee. The origin of the experimentally observed enantioselectivities was revealed by density functional calculations (B3LYP/6-31G*) on the transition structures of several model reactions.
Zhang
Hai-Le
HL
Key Laboratory for Asymmetric Synthesis and Chirotechnology of Sichuan Province, Chengdu Institute of Organic Chemistry Chinese Academy of Sciences, Chengdu, 610041, China.
Jiang
Fan
F
Zhang
Xiao-Mei
XM
Cui
Xin
X
Gong
Liu-Zhu
LZ
Mi
Ai-Qiao
AQ
Jiang
Yao-Zhong
YZ
Wu
Yun-Dong
YD
D000478:Alkylation; D004983:Ethanolamines / Q000138:chemical synthesis / Q000737:chemistry*; D007097:Imines / Q000138:chemical synthesis*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
D004983:Ethanolamines; D007097:Imines; D008024:Ligands; D009942:Organometallic Compounds; C007514:diphenylaminoethanol; D015032:Zinc