A facile synthesis of 4-tetrazolyl-4H-3,1-benzoxazines by a Passerini-azide/acylation/catalytic aza-Wittig sequence was developed. The Passerini-azide reactions of 2-azidobenzaldehydes, trimethylsilyl azide and isocyanides produced tetrazoles, which were further acylated to give the azides in 28-74% overall yields. The catalytic aza-Wittig reactions of the azides generated 4-tetrazolyl-4H-3,1-benzoxazines in good yields, by using a catalytic amount of 3-methyl-1-phenyl phospholene-1-oxide (10 mol%) and TMDS/Ti(i-PrO)4reductant s...
