Mechanism of the gold(I)-catalyzed Rautenstrauch rearrangement: a center-to-helix-to-center chirality transfer.
The mechanism of the stereospecific gold(I)-catalyzed Rautenstrauch rearrangement of (E)-1-ethynyl-2-methyl-but-2-en-yl acetate to 3,4-dimethyl-cyclopent-2-enone has been computationally addressed using DFT (B3LYP/6-31G, SDD for Au). Our results indicate that the bond formation event follows the Au(I)-induced acetyl transfer to the vicinal alkyne and that it is the helicity of the pentadienyl cation intermediate which keeps memory of the chiral information. The fidelity of the center-to-helix-to-center chirality transfer requires that the rates of helix interconversion and pivaloyl rotation are slower than the cyclization, as calculations predict.
Departamento de Quimica Orgánica, Universidade de Vigo, Lagoas Marcosende, 36310 Vigo, Spain.
Olalla Nieto
ON
Faza
Carlos Silva
CS
López
Rosana
R
Alvarez
Angel R
AR
de Lera