20763-19-3Relevant articles and documents
Total Synthesis of Liangshanone
Huang, Hong-Xiu,Mi, Fen,Li, Chunxin,He, Huan,Wang, Feng-Peng,Liu, Xiao-Yu,Qin, Yong
, p. 23609 - 23614 (2020)
The first total synthesis of liangshanone, a hexacyclic ent-kaurane diterpenoid alkaloid, has been completed. Its intricate cagelike framework was assembled through several key transformations, including an oxidative dearomatization/Diels–Alder (OD/DA) cycloaddition sequence, a tandem alkene cleavage/Mannich cyclization, a Robinson-type annulation, and an intramolecular aldol reaction. Notably, an organocatalytic enantioselective α-hydroxymethylation process allowed the preparation of an enantiomerically enriched tricyclic intermediate that should enable asymmetric access to the target natural product.
Structure-activity relationships of synthetic tricyclic trioxanes related to artemisinin: The unexpected alkylative property of a 3- (methoxymethyl) analog
Provot, Olivier,Camuzat-Dedenis, Boris,Hamzaoui, Mohamed,Moskowitz, Henri,Mayrargue, Jo?lle,Robert, Anne,Cazelles, Jér?me,Meunier, Bernard,Zouhiri, Fatima,Desma?le, Didier,D'Angelo, Jean,Mahuteau, Jacqueline,Gay, Frédérick,Cicéron, Liliane
, p. 1935 - 1938 (1999)
A clear-cut correlation between antimalarial potency and the alkylative property of synthetic tricyclic trioxanes 5-10 is reported. Thus, trioxanes 5 and 7, substituted at the C-5a angular position by a methyl or a cyano group, proved to be completely devoid of antimalarial activity, and did not alkylate the heme model Mn(II)TPP. In contrast, both the anti-Plasmodium activity and the alkylative property were restored in the C-5a-unsubstituted analog 8, bearing a methoxymethyl group at C-3. Reaction of 8 with Mn(II)TPP furnished the covalent adduct 18, resulting from trapping of the methoxymethyl radical by the heine model. All these results reinforce the hypothesis that the metalloporphyrin closely interacts with the peroxide bond of the drug to bring about activation of these trioxane antimalarial agents.
Intramolecular anodic olefin coupling reactions: The use of allylsilane coupling partners with allylic alkoxy groups
Frey, Dean A.,Reddy, S. Hari Krishna,Moeller, Kevin D.
, p. 2805 - 2813 (1999)
Intramolecular anodic olefin coupling reactions having an alkoxy substituent on the allylic carbon of an allylsilane moiety have been studied. These substrates were examined as part of an effort to determine the compatibility of the anodic olefin coupling reaction with the presence of very acid-sensitive functional groups and the construction of functionalized five-membered rings. In the initial experiment reported, an enol ether moiety was coupled to a trisubstituted allylsilane to afford a five-membered ring product without loss of the allylic alkoxy group. The reaction was stereoselective and could be used to generate a five-membered ring with three contiguous asymmetric centers. The stereochemical outcome of the reaction was best explained by a "pseudoequatorial" alkoxy group in the transition state; an argument that implied the reaction was under kinetic control. This suggestion was tested with the use of two electrolysis substrates that led to identical products through different transition states. The two substrates led to much different product ratios, proving that the reactions were not controlled by thermodynamics but rather governed by kinetic control. This observation was opposite to the conclusion reached with earlier vinylsilane-based substrates. Finally, the reactions were shown to be compatible with the presence of the alkoxy group even when challenged to form a fused bicyclic ring skeleton and a quaternary carbon. As in the initial case, the reaction to form a quaternary carbon was also highly stereoselective.
6,19-carbon-bridged steroids. Synthesis of 6,19-methanoprogesterone.
Joselevich, Maria,Ghini, Alberto A,Burton, Gerardo
, p. 939 - 943 (2003)
6,19-Methanoprogesterone (4) was synthesized in nine steps from the readily available 3 beta,20 beta-diacetyloxy-5 alpha-bromo-6,19-oxidopregnane (5) in 14% overall yield. The additional carbon atom was introduced by reaction of a C-19 aldehyde with Ph3PC
Visible-light induced metal-free cascade Wittig/hydroalkylation reactions
Miao, Pannan,Li, Ruining,Lin, Xianfeng,Rao, Liangming,Sun, Zhankui
supporting information, p. 1638 - 1641 (2021/03/09)
Cascade reactions are green and powerful transformations for building multiple carbon-carbon bonds in one step. Through a relay olefination and radical addition process, we were able to develop the cascade Wittig/hydroalkylation reactions induced by visible light. This metal-free radical approach features mild conditions, robustness, and excellent functionality compatibility. It allows access to saturated C3 homologation products directly from aldehydes or ketones. The synthetic utility of this method is demonstrated by a two-step synthesis ofindolizidine 209D.
Catalytic α-Selective Deuteration of Styrene Derivatives
Puleo, Thomas R.,Strong, Alivia J.,Bandar, Jeffrey S.
supporting information, p. 1467 - 1472 (2019/01/25)
We report an operationally simple protocol for the catalytic α-deuteration of styrenes. This process proceeds via the base-catalyzed reversible addition of methanol to styrenes in DMSO-d6 solvent. The concentration of methanol is shown to be critical for high yields and selectivities over multiple competing side reactions. The synthetic utility of α-deuterated styrenes for accessing deuterium-labeled chiral benzylic stereocenters is demonstrated.
