In the present study, a practical method to prepare piperazinyl amides of 18β-glycyrrhetinic acid was developed. Two main procedures for the construction of important intermediate are discussed. One procedure involves the amidation of 1-Boc-piperazine with 3-acetyl-18β-glycyrrhetinic acid, prepared by the reaction of 18β-glycyrrhetinic acid with acetic anhydride without any solvent at 130 °C. The other procedure to prepare compound involves the amidation of 18β-glycyrrhetinic acid followed by the esterification with acetic anhydride. Finally, compound underwent -Boc deprotection to prepare product . To ascertain the scope of the reaction, another C-3 ester derivative was tested under the optimized reaction conditions. Furthermore, the reasons for the appearance of byproducts were elucidated. Crystallographic data of a selected piperazinyl amide is reported.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188925 | PMC |
http://dx.doi.org/10.3762/bjoc.16.73 | DOI Listing |
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