Synthesis of lupane and a-secolupane allylamides
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Lupane C-28 monoallylamides with α-ketoxime and α-hydroxyoxime groups in ring A were prepared from betulonic acid. Formation of A-secolupane C-3(28) mono- and diallylamides was used as an example to demonstrate that a one-step synthesis of 2,3-secotriterpene amides was possible by fragmentation of betulin and betulonic acid α-oximes by oxalylchloride or thionylchloride with subsequent amidation of the 2,3-secotriterpenoic acids formed in situ by allylamine. The proposed method enabled the yield of 2,3-secolupane C-3,C-28 diamides to be increased by five times compared with the previously described five-step method for preparing A-secotriterpene amides from betulonic acid.
KeywordsBeckmann fragmentation A-secotriterpenoids betulin betulonic acid allylamine amides
The work was supported financially by the FTP “Research and Development on Priority Directions in the Development of the Russian Science and Technology Complex for 2007-2013” (State Contract No. 11.519.11.2033); RAS Presidium Program (No. 12-P-3-1009); and the RFBR (Grant No. 11-03-96003-r_ural_a).
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