6 k2\,-cop years ago by Jacobs and Craig6 and Robinson.'If the 3-carboxyl group is retained through the ring-closure reaction, the crucial question becomes whether it can be easily removed or not. The second point of variation hinges upon whether acetaldehyde or pyruvic acid is the ring-closure reagent for the formation of the@-carboline ring. Both reagents react readily under “physiological conditions” to give the ring system, but it has long been ...
![3-oxo-1,2,5,6,11,11b-hexahydroindolizino[8,7-b]indole-5-carboxylic acid结构式](https://image.chemsrc.com/caspic/266/73198-04-6.png)
![2,3,4,9-四氢-1H-吡啶并[3,4-b]吲哚-1,3-二羧酸结构式](https://image.chemsrc.com/caspic/221/59132-30-8.png)
