OH product showed two carbonyl stretching frequencies (1707 and 1725 cm-'for 4, 1710 and 1725 cm-'for 5), indicative of the presence of two carbonyl groups in each compound. In addition, characteristic branched COC stretch bands were observed at 1143-1105 cm-'.'H NMR and I9F NMR spectra of the two products allowed unequivocal assignment of their structures. The presence of a singlet between 2.10 and 2.20 ppm and of a pair of ...