6023-73-0Relevant academic research and scientific papers
Palladium-Catalyzed Allylic Alkylation via Photocatalytic Nucleophile Generation
Shen, Yang,Dai, Zhen-Yao,Zhang, Cheng,Wang, Pu-Sheng
, p. 6757 - 6762 (2021)
The rapid assembly of an easily accessible terminal alkene, an aliphatic C(sp3)-H coupling partner, and allyl carbonate has been established by merging hydrogen atom transfer photocatalyst-mediated nucleophile generation and palladium-catalyzed allylic alkylation. The synthetic utility of this strategy is embodied by a concise synthesis of (±)-mesembrine. Mechanistic studies suggest that this protocol proceeds via a radical/ionic relay process, and a carbanionic species serves as a key intermediate for nucleophile attack on π-allylpalladium through a classic two-electron allylation pathway. This protocol showcases an atom-economic and environmentally friendly method to generate a nonstabilized nucleophile for transition-metal catalysis.
Stereoselectivity in the organoiron-mediated synthesis of (±)-mesembrine
Roe, Caroline,Sandoe, Elizabeth J.,Stephenson, G. Richard,Anson, Christopher E.
, p. 650 - 653 (2008)
The preparation and structural characterisation of a 1-aryl-substituted electrophilic η5-cyclohexadienyliron complex with the correct functionalisation as a 'C12 building block' for the synthesis of (±)-mesembrine establishes the accessibility of a flattened conformation to allow nucleophile addition ipso to the arene. The chirality relay in quaternary centre formation by nucleophile addition has been confirmed, and the product has been converted into the Sceletium alkaloid mesembrine.
Palladium-catalyzed asymmetric direct intermolecular allylation of α-aryl cyclic vinylogous esters: Divergent synthesis of (+)-oxomaritidine and (?)-mesembrine
Wang, Wei,Dai, Jun,Yang, Qiqiong,Deng, Yu-Hua,Peng, Fangzhi,Shao, Zhihui
, p. 920 - 924 (2021/02/16)
We demonstrate that α-aryl cyclic vinylogous esters are competent substrates in the direct intermolecular Pd-catalyzed asymmetric allylic alkylation, enabling a straightforward enantioselective synthesis of 6-allyl-6-aryl-3-ethoxycyclohex-2-en-1-ones, common motifs embedded in numerous structurally diverse natural products. As an initial demonstration of the utility of this protocol, the first catalytic enantioselective total synthesis of (+)-oxomaritidine and an improved five-step catalytic enantioselective synthesis of (?)-mesembrine have been completed divergently.
A Concise Total Synthesis of (±)-Mesembrine
Kim, Hyoungsu,Choi, Hosam,Lee, Kiyoun
, p. 1203 - 1206 (2018/02/26)
A concise total synthesis of (±)-mesembrine has been successfully accomplished in seven steps and 24% overall yield from commercially available 3-ethoxy-2-cyclohexen-1-one. Central to the assembly of the skeleton of mesembrine are a Johnson-Claisen rearra
A Concise Total Synthesis of (-)-Mesembrine
Wang, Lu-Ning,Cui, Qi,Yu, Zhi-Xiang
, p. 10165 - 10171 (2016/11/17)
A concise total synthesis of mesembrine (four steps from known compound) was achieved both racemically and asymmetrically. Two key reactions were used here. One is the Rh(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropane 3c and CO. The other one is Buchwald's Pd-catalyzed coupling reaction that coupled β,γ-cyclohexenone 2c with aryl bromide 5 (using dppe ligand for racemic or (S)-Antphos ligand for asymmetric synthesis) to give γ,γ-disubstituted α,β-cyclohexenone 1c. Finally, aza-Michael addition converted 1c to mesembrine.
Highly chemoselective aerobic oxidation of amino alcohols into amino carbonyl compounds
Sasano, Yusuke,Nagasawa, Shota,Yamazaki, Mai,Shibuya, Masatoshi,Park, Jaiwook,Iwabuchi, Yoshiharu
supporting information, p. 3236 - 3240 (2014/04/03)
The direct oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has often posed serious challenges in organic synthesis and has constrained chemists to adopting an indirect route, such as a protection/deprotection strategy, to attain their goal. Described herein is a highly chemoselective aerobic oxidation of unprotected amino alcohols to their amino carbonyl compounds in which 2-azaadamantane N-oxyl (AZADO)/copper catalysis is used. The catalytic system developed leads to the alcohol-selective oxidation of various unprotected amino alcohols, carrying a primary, secondary, or tertiary amino group, in good to high yield at ambient temperature with exposure to air, thus offering flexibility in the synthesis of nitrogen-containing compounds. Strong as an ox: The highly chemoselective aerobic oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has been achieved by using 2-azaadamantane N-oxyl (AZADO)/copper catalysis. This catalytic system oxidizes not only alcohols with tertiary amino groups but also those with secondary and primary amines in good to high yield at ambient temperature in air. bpy=2,2-bipyridyl, DMAP=4-(N,N-dimethylamino)pyridine.
'Aromatic ring umpolung', a rapid access to the main core of several natural products
Guérard, Kimiaka C.,Sabot, Cyrille,Beaulieu, Marc-André,Giroux, Marc-André,Canesi, Sylvain
scheme or table, p. 5893 - 5901 (2010/09/09)
Treatment of various substituted phenols in the presence of (diacetoxyiodo)benzene promotes the formation of a phenoxenium ion, a very electrophilic species able to react with various nucleophiles leading rapidly to a plethora of different cores present i
Palladium-catalyzed sequential arylation and allylic alkylation of highly functionalized ketones: A concise synthesis of mesembrine
Zhao, Yuanhong,Zhou, Yongyun,Liang, Leilei,Yang, Xiaodong,Du, Fengxiang,Li, Ang,Zhang, Hongbin
supporting information; experimental part, p. 555 - 558 (2009/07/25)
(Chemical Equation Presented) An unprecedented palladium-catalyzed sequential procedure toward arylation and allylic alkylation of highly functionalized cyclohexenones was developed. This new protocol leads to useful building blocks containing a benzylic
Consecutive sigmatropic rearrangements in the enantioselective total synthesis of (-)-joubertinamine and (-)-mesembrine
Ilardi, Elizabeth A.,Isaacman, Michael J.,Qin, Ying-chuan,Shelly, Sommer A.,Zakarian, Armen
experimental part, p. 3261 - 3269 (2009/08/15)
Joubertinamine and mesembrine are two related alkaloids isolated from Sceletium plants. From the perspective of chemical synthesis, the major challenge posed by joubertinamine and mesembrine is undoubtedly the construction of the benzylic quaternary stere
Oxidative Friedel-Crafts reaction and its application to the total syntheses of Amaryllidaceae alkaloids
Guerard, Kimiaka C.,Sabot, Cyrille,Racicot, Leanne,Canesi, Sylvain
experimental part, p. 2039 - 2045 (2009/07/01)
An oxidative Friedel-Crafts reaction involving different aromatic compounds mediated by a hypervalent iodine reagent has been performed, using polysubstituted phenols. The strategy fits within the concept of "aromatic ring umpolung", which opens up novel
