Photochemistry of cyclic azo-compounds: preparation of highly strained spiro-compounds
Abstract
Photofragmentation of spiro-3H-pyrazoles (1) having ring bridges of different size, affords spiro[2.5]-octatrienes (2a–e) or spiro[2.6]nonatetraenes (2f, g), which, in a few cases, undergo an additional [1,7]-H-shift to (3) and (4).