New bisfuran derivative from sarsasapogenin

Synthesis, Crystal Structure and Bioactivities of N-(5-(4-chlorobenzyl)-1,3,5-Triazinan-2-Ylidene)Nitramide

“…The distances of resemble guanidine structures with nitro group were found in literatures with similar values from 1.342 to 1.389 Å [34][35][36][37]41,42]. However, these distance values were longer than those of reported C=N bonds with nitro group with values between 1.267 and 1.275 Å [43][44][45][46][47]. Bracuti commented molecular interaction and intermolecular H-bonds in crystal structure had responsibilities for this elongation of hydrazine C=N bond [37].…”

Steroids: partial synthesis in medicinal chemistry

“…139,140 Diosgenin has provided a readily available starting material for the partial synthesis of 22-deoxyOSW-I 39 141 which has potent anti-tumour activity, for the preparation of 22,23dioxocholestanes, 142 16b-hydroxy-5a-cholestane-3,6-dione, 143 and methyl protodioscin. 144 Various aspects of the chemistry of the spirostan ring system have been explored, including the acetoxylation at C-23, 145 the oxidation and rearrangements to form a bis-furan 40 146 and the nucleophilic substitution of 26-iodopseudodiosgenin. 147 The antifungal activity of steroidal saponins has been investigated.…”

Unusual Reactions of a 7,17-seco-type C19-Diterpenoid Alkaloid Derived from Deltaline

“…Migration of an alkoxy group is very uncommon in the pinacol-like rearrangements. As far as we know, only Lόpez et al [6] and Cyrański et al [7] have reported that the pinacol-like rearrangement of steroid 14, possessing a vicinal di-hemiketal, yielded 22-oxo-23-spiroketal (15) via migration of the alkoxy group (Scheme 5). In the present study, treatment of 7,17-seco-type diterpenoid alkaloid 3 with triethylamine (120 o C) gave the pinacol-like rearrangement product 7 with an uncommon alkoxy group migration.…”

“…The formation of compounds 6 and 7 might be explained by the mechanism depicted in Scheme 3. Compound 7 might be formed by a semipinacol rearrangement of allylic alcohol A [6], involving migration of an alkoxy group. A pinacol rearrangement is typically catalyzed by acid; however, this pinacol-like rearrangement was accomplished under basic condition.…”