Mechanism of the gold-catalyzed rearrangement of (3-acyloxyprop-1-ynyl)oxiranes: a dual role of the catalyst.
The three competing paths for the rearrangement of 1 (involving 1,2- and 1,3-ester migration with alkyne or oxirane activation) evidence the multifaceted character of gold as a catalyst. The most favorable mechanism for this useful synthetic transformation involves a cascade of more than eight steps. All the functional groups in the substrate play a crucial and synergistic role, and sequential gold coordination to both the pi-system and the lone pairs of oxygen is needed. Exploration of these three paths suggests the use of a nonalkynophilic Lewis acid (BF(3)) as a possible synthetic alternative for this transformation.
González Pérez
Adán
A
Departamento de Quimica Organica, Facultade de Quimica, Universidade de Vigo, 36310 As Lagoas-Marcosende s/n, Spain.
Silva López
Carlos
C
Marco-Contelles
José
J
Nieto Faza
Olalla
O
Soriano
Elena
E
de Lera
Angel R
AR