Regioselective Spirostan E-Ring Opening for the Synthesis of Dihydropyran Steroidal Frameworks
作者:J. Ciciolil Hilario-Martínez、Reyna Zeferino-Díaz、Miguel A. Muñoz-Hernández、Ma. Guadalupe Hernández-Linares、José Luis Cabellos、Gabriel Merino、Jesús Sandoval-Ramírez、Zhendong Jin、María A. Fernández-Herrera
DOI:10.1021/acs.orglett.6b00492
日期:2016.4.15
The regioselective opening of the ring E in spirostan sapogenins provides new dihydropyran derivatives. This novel side chain is obtained after a Lewis acid mediated acetolysis followed by an alkaline workup. The reaction mechanism is analyzed via density functional theory computations, and both experimental and computational data support the formation of an oxacarbenium intermediate. The behavior
-one), the principal neurosteroid acting via γ-aminobutyric acid (GABA). These analogues were designed to study the structural requirements of the corresponding GABAA receptor. Their biological activity was measured by in vitro test with [3H]flunitrazepam as radioligand in which allopregnanolone and its active analogues stimulated the binding to the GABAA receptor. Analysis of the SAR data suggests
作者:Shashi B. Mahato、Niranjan P. Sahu、Amar N. Ganguly、Kazumoto Miyahara、Toshio Kawasaki
DOI:10.1039/p19810002405
日期:——
Besides β-sitosterol-β-D-glucoside and dioscin, two new steroidalglycosides, neohecogenin glucoside and tribulosin, isolated from the aerial part of TribulusterrestrisLinn. were respectively shown to be neohecogenin-3-O-β-D-glucopyranoside (2) and neotigogenin-3-O-β-D-xylopyranosyl(1→2)-[β-D-xylopyranosyl(1→3)]-β-D-glucopyranosyl(1→4)-[α-L-rhamnopyranosyl(1→2)]-β-D-galactopyranoside (7).
除了β谷甾醇-β- d葡糖苷和薯蓣皂甙,两个新的甾体糖苷,neohecogenin葡糖苷和tribulosin,从地上部分分离蒺藜属。分别示出为neohecogenin -3- ö -β- d吡喃葡萄糖苷(2)和neotigogenin -3- ö -β- d -xylopyranosyl(1→2) - [β- d -xylopyranosyl(1→3)] - β- D-吡喃葡萄糖基(1→4)-[α- L-鼠李糖吡喃糖基(1→2)]-β- D-吡喃半乳糖苷(7)。
Site‐Selective Pyridine C−H Alkylation with Alcohols and Thiols via Single‐Electron Transfer of Frustrated Lewis Pairs
作者:Chang‐Yin Tan、Myojeong Kim、Inyoung Park、Yuhyun Kim、Sungwoo Hong
DOI:10.1002/anie.202213857
日期:2022.12.19
A unified strategy for the deoxygenative or desulfurative pyridylation of various alcohols and thiols was developed through SET of FLPs derived from pyridinium salts and PtBu3. This method provides an opportunity for the selective heteroarylation of a diverse range of alcohols and thiols, and the versatility of this protocol was further demonstrated by the successful modification of pharmaceutically
通过衍生自吡啶盐和 P t Bu 3的 FLP 的 SET,开发了一种用于各种醇和硫醇的脱氧或脱硫吡啶基化的统一策略。该方法为多种醇和硫醇的选择性异质化提供了机会,并且通过成功修改药学相关分子进一步证明了该协议的多功能性。
Synthesis of a new cytotoxic cephalostatin/ritterazine analogue from hecogenin and 22-epi-hippuristanol
A new cephalostatin/ritterazine analogue was prepared from the commercially available hecogenin acetate and the natural cytotoxic steroid 22-epi-hippuristanol. The method involved the reductive dimerization of enaminoketones (condensation of alpha-aminoketones) and condensation between an enaminoketone and an alpha-hydroxyketone. The new analogue showed higher cytotoxic activity than the cytotoxic 22-epi-hippuristanol against MDA-MB-231, A-549 and HT-29 cultured tumor cell lines. (C) 2009 Elsevier Ltd. All rights reserved.