Structure and reaction pathway of TMP-Zincate: amido base or alkyl base?
The novel directed ortho metalation (DoM) reagents for functionalized aromatic rings, TMP-Zn-ates (R2Zn(TMP)Li (R = Me, 1; tBu, 2)), have been reported to be synthetically useful for the chemo- and regioselective construction of multi-functionalized aromatic compounds. Here, we present the first comprehensive structural and mechanistic investigation by means of X-ray, NMR, and DFT studies on the DoM reaction employing our original TMP-Zn-ate base. The structures of TMP-Zn-ates in solution and in the solid state were determined. The DFT study strongly suggested that the deprotonation involving the TMP ligand on the TMP-Zn-ate is kinetically more favorable than that involving the alkyl ligand, and this view was supported by monitoring of the 13C NMR spectrum of the reaction mixture.
Uchiyama
Masanobu
M
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. uchiyama@mol.f.u-tokyo.ac.jp
Matsumoto
Yotaro
Y
Nobuto
Daisuke
D
Furuyama
Taniyuki
T
Yamaguchi
Kentaro
K
Morokuma
Keiji
K
D018360:Crystallography, X-Ray; D008094:Lithium / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010880:Piperidines / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D009942:Organometallic Compounds; D010880:Piperidines; D008094:Lithium; D015032:Zinc