[A simple method for preparation of 18alpha-glycyrretinic acid ant its derivatives]
D V Ignatov1, Iu I Prokof'ev, O M Ipatova
1Orekhovich Research Institute of Biomedicinal Chemistry, Russian Academy of Medical Sciences, Pogodinskaya ul. 10, Moscow, 119832 Russia.
Abstract:
Treatment of 18 beta-glycyrrhizic acid with a methanolic solution of HCl resulted in a 1:1 mixture of methyl esters of 18 alpha- and 18 beta-glycyrrhetinic acids. Benzoylation of the mixture led to methyl esters of 3-benzoyl-18 alpha-glycyrrhetinic acid and 3-benzoyl-18 beta-glycyrrhetinic acid, which were separated by chromatography on silica gel. 18 alpha-Glycyrrhetinic acid was prepared by alkaline hydrolysis of methyl 3-benzoyl-18 alpha-glycyrrhetinate and was further used for the syntheses of 3-keto-18 alpha-glycyrrhetinic acid and methyl esters of 18 alpha-glycyrrhetinic acid and 3-keto-18 alpha-glycyrrhetinic acid.
Related Concept Videos
Preparation of Acid Anhydrides
The carboxylate ion acts as a nucleophile that attacks the carbonyl carbon of the acid chloride to form a tetrahedral intermediate. Subsequently, the re-formation of the carbonyl group with the loss of the chloride ion as a leaving group leads to the formation of an acid...
Preparation of 1° Amines: Gabriel Synthesis
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Preparation of Carboxylic Acids: Carboxylation of Grignard Reagents
Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Preparation of Carboxylic Acids: Overview
Preparation of Aldehydes and Ketones from Carboxylic Acid Derivatives
Carboxylic acid derivatives like acid chlorides and esters are more easily reducible than the corresponding acids. The derivatives reduce in the presence of mild reducing agents to give aldehydes. Aldehydes can also be prepared by Rosenmund reduction, that is, the reduction of acid...
