Photoreactions of 1-(3-hydroxy-2-pyridyl)-2-(pentamethyldisilanyl)ethyne, aza analogue of 1-o-hydroxyphenyl-2-(pentamethyldisilanyl)ethyne

Photolysis of 1-(3-hydroxy-2-pyridyl)-2-(pentamethyldisilanyl)ethyne 1, aza analogue of 1-o-hydroxyphenyl-2-(pentamethyldisilanyl)ethyne, in benzene provides novel intramolecular cycloaddition products 6 and 8 via silacyclopropene intermediate 3 but affords a novel intramolecular cycloaddition product 10 via 1-silaallene intermediate 9 in addition to 6 and 8 in methylene chloride.