1. Generation of nitrenes by means of photolysis of arylmethylazides and its derivatives have been studies. Pyrolysis of 2-azidomethylthiophene¡]44a¡^ gave 2-thiophenecarboxaldehyde¡]77a¡^and (2-thienylmethylidene)-2-thienylamine¡]45a¡^, and pyrolysis of 2-azidomethylbenzo[b]thiophene¡]44b¡^gave the corresponding products. Pyrolysis of 2-azido-1-(2-thienyl)ethanone¡]52a¡^gave 2-thiophenecarboxaldehyde¡]77a¡^, 2-acetylthiophene¡]80a¡^and 2-(thiophene-2-carbonyl)amino-1-(2-thienyl)ethanone¡]83a¡^, and pyrolysis of 2-azido-1-(2-benzo[b]thienyl)ethanone¡]52b¡^gave the corresponding products. 2. Pyrolysis of 3-cyclohexeno[b]furylmethyl benzoate¡]35¡^gave cyclohexeno-4-methylenecyclobuten-3-one¡]25¡^via highly reactive carbene intermediate. At high temperature, compound 25 can continue the reaction of elimination and ring opening to give benzene¡]43¡^, fulvene¡]46¡^, 2-ethylnylcyclohex-1-ene carbaldehyde¡]44¡^ and 4,5-dimethylenecyclopent-2-enone¡]45¡^.