Investigation of the hydroxyl directing effect on the Paternò-Büchi reaction on 5-(2-triisopropylsilyloxazolyl)methanol derivatives

The photochemical coupling of 5-oxazoylmethanol derivatives with benzophenone and benzaldehyde showed that the hydroxyl directing effect in the Paternò-Büchi reaction described in the case of allylic alcohols and furylmethanol derivatives can also be present in the case of 5-oxazolylmethanol derivatives. In this case, the reaction with aromatic aldehydes showed an unusual endo stereoselectivity. The observed stereoselectivity can be predicted on the basis of the interaction between HSOMO and LSOMO in the biradical intermediate.

The photochemical coupling of 5-oxazoylmethanol derivatives with benzophenone and benzaldehyde showed a hydroxyl directing effect.