Few a-diketones derived from hydrindene have been studied and some phenomena observed in connection with these compounds have been incorrectly interpreted. These a- diketones may be conveniently divided into three classes corresponding to the number of activated hydrogen atoms they contain: class A having none, B one and C two.
![1H-Isoindole-1,3(2H)-dione,2-[1,1'-biphenyl]-2-yl结构式](https://image.chemsrc.com/caspic/308/14835-59-7.png)
