Catalytic asymmetric aza-Morita-Baylis-Hillman reaction of methyl acrylate: role of a bifunctional La(O-iPr)3/linked-BINOL complex.
The catalytic asymmetric aza-Morita-Baylis-Hillman reaction using unactivated methyl acrylate is described. A simple Lewis acidic metal catalyst, such as La(OTf)(3), was not suitable for the reaction, but rare earth metal alkoxide/linked-BINOL complexes possessing bifunctional Lewis acid and Brønsted base properties efficiently promoted the reaction in combination with an achiral nucleophilic organocatalyst. The combined use of a La(O-iPr)(3)/(S,S)-TMS-linked-BINOL complex with a catalytic amount of DABCO promoted the aza-Morita-Baylis-Hillman reaction of a broad range of N-diphenylphosphinoyl imines. Products from aryl, heteroaryl, and alkenyl imines were obtained in 67-99% yield and 81-95% ee. It is noteworthy that isomerizable alkyl imines could be employed as well, giving products in 78-89% yield and 94-98% ee. Initial rate kinetic studies as well as kinetic isotope effect experiments using alpha-deuterio-methyl acrylate support the importance of both the nucleophilicity of La-enolate and the Brønsted basicity of a La-catalyst for promoting the reaction.
Yukawa
Takafumi
T
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
Seelig
Bianca
B
Xu
Yingjie
Y
Morimoto
Hiroyuki
H
Matsunaga
Shigeki
S
Berkessel
Albrecht
A
Shibasaki
Masakatsu
M
D000179:Acrylates / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D007097:Imines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009284:Naphthols / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D000179:Acrylates; C406944:BINOL, naphthol; D056831:Coordination Complexes; D007097:Imines; D009284:Naphthols; D009942:Organometallic Compounds; C035956:methyl acrylate