Letters in Organic Chemistry ( Diastereoselective Paternò-Büchi Reaction on Furan Derivatives-Reaction with Asymmetric Ketones )

The photochemical reaction of 1-phenyl-2-methyl-1-butanone with furan gave propiophenone via a Norrish Type II reaction. The same behavior was observed using 1-phenyl-2-methyl-1-pentanone. In this case, the product derived from a Norrish-Yang reaction was obtained. The photochemical reaction of 2- phenylpropiophenone with furan and 2-methylfuran gave the corresponding Paternò-Büchi adducts. 2- Methylfuran gave a mixture of regioisomers. All the products of the Paternò-Büchi reaction were obtained with >98% de. The diastereoselectivity was explained by considering the relative stability of the biradical intermediates.