In a dry argon atmosphere 0.150 g of oxime 5, 0.070 g of 1,2-phenylene diamine 1 and 0.150
ml triethyl-borate are dissolved in 4 ml dry THF and heated for 24 h at 60°C. After a TLC
shows consumption of starting oxime the mixture is evaporated to dryness and the resulting
residue purified by column chromatography (eluent: hexane - ethyl acetate: 10-1 vol/vol) to
give 0.171 g (92 %) of the diazo-amine intermediate 6.
Replacing the B(OEt)3 by 2.5 g of basic AI2O3 and the THF by 2 ml of xylene and heating this
mixture to 140°C for 48 h gives after the usual work-up 0.089 mg of diazo compound 6 and
0.300 g of starting oxime 5.
According the procedure given for the preparation of compound 4 in example 1, triazole 7 is
obtained from 0.007 g (0.016 mmol) of intermediate amine 6 and 0.020 g (0.122 mmol) CuSO4
in 100% (0.007 g). In this comparative example, 7.73 equivalents of copper salt are used.
