1. Brückner, R.; Peiseler, B. Tetrahedron Lett. 1988, 29, 5233–5236.
2. van Leusen, A. M.; Strating, J. Org. Synth. 1977, 57, 95–102. This procedure is based on the work of Strating and van Leusen (van Leusen, A. M.; Strating, J. Rec. Trav. Chim. Pays-Bas 1965, 84, 151–164 and references cited therein), who discovered this class of diazo compounds.
3. Most of the crude samples of 1a thus obtained appeared pure in NMR. In a few cases, however, a weak singlet at 6.8 ppm, possibly indicative of the presence of 1,2-bis-tosylethylene, was also perceptible in the 1H NMR spectra.
4. Sulfones 1 cannot be obtained from the corresponding p-tolyl alkylsulfones by using the diazo transfer method of Regitz (see: Dieckmann, J. J. Org. Chem. 1965, 30, 2272–2275). Recently, a procedure based on the related alumina-induced decomposition of 1-diazo-1-tosyl-acetophenone has been proposed (Korneev, S.; Richter, C. Synthesis 1995, 1248–1250). However, owing to the ease with which the starting carbamate 2a is prepared, this method presents no clear advantage over the van Leusen’s process.
5. Lee, J. G.; Kwak, K. H.; Hwang, J. P. Tetrahedron Lett. 1990, 31, 6677–6680.