Double diastereoselection in aldol reactions mediated by dicyclohexylchloroborane between L-erythrulose derivatives and chiral aldehydes. The Felkin-Anh versus Cornforth dichotomy.
Both matched and mismatched diastereoselections have been observed in aldol reactions of the B,B-dicyclohexylboron enolate of a protected l-erythrulose derivative with a range of chiral aldehydes. The stereochemical outcome of reactions with alpha-methyl aldehydes can be adequately explained within the Felkin-Anh paradigm. In the case of alpha-oxygenated aldehydes, however, strict adherence to this model does not allow for a satisfactory account of the observed results. In such cases, the Cornforth model provides a much better explanation.
Marco
J Alberto
JA
Departamento de Química Orgánica, Universidad de Valencia, E-46100 Burjassot, Valencia, Spain. alberto.marco@uv.es
Carda
Miguel
M
Díaz-Oltra
Santiago
S
Murga
Juan
J
Falomir
Eva
E
Roeper
Harald
H