The mechanism of the Schmidt rearrangement has been examined in the conversion of chromanones to 1,4- and 1,5-benzoxazepinones. With substituents in the 6-, 7-, or 8-position, only electronic effects prevail resulting in the exclusive formation of 1,4-benzoxazepinones. Steric effects come into play with increasing bulk of substituents in the 5-position of the chromanone. Results now presented favor more than one pathway for the products to arise. Nuclear magnetic resonance spectra have been used to distinguish between the isomeric 1,4- and 1,5-benzoxazepinones.Several new chromanones have been synthesized.
Schmidt重排反应机理已经在将香豆酮转化为1,4-和1,5-苯并噁唑烷酮过程中进行了研究。在6、7或8位有取代基的情况下,只有电子效应起作用,导致仅形成1,4-苯并噁唑烷酮。当香豆酮的5位取代基增大时,立体效应开始发挥作用。现在呈现的结果支持产物形成的多条途径。核磁共振谱被用来区分异构体1,4-和1,5-苯并噁唑烷酮。已合成了几种新的香豆酮。