1.
Nat Prod Commun
; 11(4): 449-52, 2016 Apr.
Artigo
em Inglês
| MEDLINE
| ID: mdl-27396190
RESUMO
Stereospecific oxidation of diacetoxyheterobetulin with ozone and dimethyldioxirane led to 3ß,28-diacetoxy-18α,19ßH-urs-20α,21α-epoxide with yields of 79% and 87%, respectively. Oxidation with ozone was not selective and gave two minor products containing 2lα-hydroxy-20(30)-ene and 21a-hydroxy-20ß,28-epoxy-fragments in ring E. The structures of 3ß,28-diacetoxy-18α,19ßH-urs-20α,21α-epoxide and 3ß-diacetoxy-21α-hydroxy-20ß,28-epoxy-18α,19ßH-ursane were confirmed by X-ray analysis for the first time.