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.
Keywords: diastereoselectivity, chiral ketone, 2+2 cycloaddition, Paterno-Buchi reaction
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