Baeyer-Villiger spectroscopy

In the Baeyer-Villiger oxidation of [4.3.3]propellane-8,ll-dione 74 the propellane-bis-lactones formed, 75 and 76, are accompanied by a dispirolactone 77 22. Different product mixtures result when different (acidic or more basic) reaction conditions are employed but it has been shown experimentally for the head-to-tail propellane bis-lactone 75, vis-a-vis the isomeric dispiran 77, the latter appears to be the thermodynamically more stable product, resulting from the former under acidic conditions (p-TsOH/ C6H6, 7 days, r.t.). The structures were established by means of X-ray diffraction and H- and 13C-NMR spectroscopy. 

When a cyclization reaction leads to mixtures of two isomeric benzo[6]thiophenes, their relative proportions are readily estimated by examination of the 1H NMR spectrum of the mixture.96 104-106 Mixtures obtained by acetylation98 and bromination 76,90 reactions and by Baeyer-Villiger oxidation of acetylbenzo[6]thiophenes107 have been similarly analyzed. The 19F NMR spectra of several polyfluoro-benzo[6]thiophenes have been examined,103,108-m and used to study the reaction of 4,5,6,7-tetrafluorobenzo[6]thiophene with nucleophiles.108 The tautomerism of 2-amino-,112-114 3-N-phenylamino-,116 and 3-hydroxybenzo[6]thiophene109,116-117 derivatives has been studied by 7H NMR spectroscopy. 

An investigation into the migratory aptitudes of C-2 versus C-4 in Beckmann, Schmidt, and Baeyer-Villiger reactions employed 13C n.m.r. spectroscopy and demonstrated that all reactions proceeded with migration of both C-2 and C-4... 

Synthesis of mesoporous molecular sieves MCM-41 and MCM-48 was carried out under microwave and hydrothermal conditions. Molecular sieves prepared were characterized using X-ray powder diffraction, scanning electron microscopy, nitrogen adsorption isotherms and infrared spectroscopy to evaluate the properties of these materials. It was observed that mesoporous molecular sieves synthesized under microwave conditions exhibit higher activity in oxidation of adamantanone by hydrogen peroxide to the respective lactone (Baeyer-Villiger oxidation). 

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