The utility of the nitrogen extrusion reaction of azido complexes, generated in situ from the corresponding aldehydes or ketones with TMSN3 in the presence of ZrCl4 or TfOH, has been described. These azido complexes could undergo three different pathways, depending on the substrates. First, azido methanolate complexes or imine diazonium ions could lead to benzisoxazole products via an intramolecular nucleophilic substitution. Second, imine diazonium ions could also undergo either the elimination of proton to provide nitrile products in good to excellent yields or an aryl migration, followed by an intramolecular nucleophilic addition, to give benzoxazole products in good yields.
US4110116A
申请人:——
公开号:US4110116A
公开(公告)日:1978-08-29
Fogged direct positive silver halide emulsion containing a cyanine dye
申请人:Minnesota Mining and Manufacturing Company
公开号:US04110116A1
公开(公告)日:1978-08-29
New cyanine dyes derived from di-halogen-benzoxazoles and benzothiazoles are desensitizers for silver halide negative emulsions and useful electron acceptor spectral sensitizers for direct positive silver halide emulsions.