61175-92-6Relevant academic research and scientific papers
Formal Synthesis of (-)-Siccanin Using an Enantioselective Domino Wacker/Carbonylation/Methoxylation Reaction
Tietze, Lutz F.,Jackenkroll, Stefan,Ganapathy, Dhandapani,Reiner, Johannes R.
, p. 96 - 100 (2016)
A formal synthesis of (-)-siccanin was achieved through an enantioselective domino Wacker/carbonylation/methoxylation reaction as the key step to form the chroman ring with a quaternary stereogenic center with 95% ee. The pendant cyclohexyl moiety was introduced through a two-step aldol condensation.
Total Synthesis and Assignment of the Absolute Configuration of (+)-Omphalic Acid
Chen, Renzhi,Qiu, Dongsheng,Lei, Xin,Niu, Yujie,Hua, Yuhui,Peng, Huayu,Zeng, Tao,Zhang, Yandong
supporting information, p. 6972 - 6976 (2021/09/08)
Omphalane diterpenoids usually contain a cyclohexane-fused bicyclo[3.2.1]octane scaffold embedded with two continuous quaternary carbon centers, which pose considerable challenges to synthetic chemists. Herein, we reported the first total synthesis of omphalic acid with high stereochemical control, featuring an intermolecular Diels-Alder cycloaddition, ring reorganization through Criegee oxidative cleavage and programmed aldol condensations, conformationally controlled hydrogenation, and Pd-catalyzed carboxylation. The absolute configuration of omphalic acid was defined for the first time via the asymmetric total synthesis facilitated by a derivatization resolution protocol.
Total Synthesis of (-)-Xylogranatopyridine B via a Palladium-Catalyzed Oxidative Stannylation of Enones
Schuppe, Alexander W.,Huang, David,Chen, Yifeng,Newhouse, Timothy R.
supporting information, p. 2062 - 2066 (2018/02/19)
We report a total synthesis of the pyridine-containing limonoid alkaloid (-)-xylogranatopyridine B in 11 steps from commercially available dihydrocarvone. The central pyridine ring was assembled by a late-stage fragment coupling approach employing a modified Liebeskind pyridine synthesis. One fragment was prepared by an allyl-palladium catalyzed oxidative enone β-stannylation, in which the key bimetallic β-stannyl palladium enolate intermediate undergoes a β-hydride elimination. This methodology also allowed introduction of alkyl and silyl groups to the β-position of enones.
Convergent formal syntheses of (±)-brussonol and (±)-abrotanone via an intramolecular Marson-type cyclization
Martinez-Solorio, Dionicio,Jennings, Michael P.
supporting information; experimental part, p. 189 - 192 (2009/06/20)
The formal convergent syntheses of both (±)-brussonol and (±)-abrotanone are reported. The key step involved the diastereoselective capture of an in situ generated oxocarbenium cation via an intramolecular Friedel-Crafts/Marson-type cyclization.
Stille-heck coupling sequences applied in a versatile new access to steroid skeletons
Suennemann, Hans Wolf,Hofmeister, Anja,Magull, Joerg,De Meijere, Armin
, p. 3739 - 3756 (2008/02/08)
A variety of enantiomerically pure steroidal compounds was synthesized utilizing a sequence of Stille and Heck cross-coupling reactions and subsequent thermal 6π-electrocyclizations. Highly chemoselective Stille couplings on the triflate moiety of several
First approach to the frondosin C ring system via a tandem cyclization/Claisen rearrangement sequence
Martinez, Isamir,Alford, Philip E.,Ovaska, Timo V.
, p. 1133 - 1135 (2007/10/03)
(Chemical Equation Presented) A one-pot tandem 5-exo cyclization/Claisen rearrangement strategy is utilized as the key step in the straightforward construction of the tetracyclic ring system of frondosin C. This reaction is done under microwave irradiatio
Photoinduced Electron Transfer Reactions of α-Cyclopropyl- And α-Epoxy Ketones. Tandem Fragmentation-Cyclization to Bi-, Tri-, and Spirocyclic Ketones
Kirschberg, Thorsten,Mattay, Jochen
, p. 8885 - 8896 (2007/10/03)
Reductive photoinduced electron transfer (PET) reactions have been performed with various bicyclic a-cyclopropyl-substituted ketones and tertiary amines. The reaction resulted in a regioselective cleavage of one cyclopropyl bond under formation of an exocyclic radical with an endocyclic enolate unit. In the case of bicyclic ketones with an unsaturated side chain, various bicyclic, spirocyclic, and tricyclic products are accessible via radical cyclization, depending on the position of the alkenyl substituent. In addition to triethylamine, W-silylated amines have also been used as electron donors, leading to a variety of compounds, among them are silylated fragmentation products, indicating that a proton is transferred from not only the amine radical cation but also the cationic silyl group. The intramolecular Paternoe-Buechi reaction has also been studied for cyclopropane derivatives of the jasmone type leading to tetracyclic oxetanes. Finally, α-epoxy-substituted ketones have been investigated under PET conditions, yielding ring-opened products.
The Kharasch reaction revisited: CuX3Li2-catalyzed conjugate addition reactions of Grignard reagents
Reetz, Manfred T.,Kindler, Alois
, p. C5 - C7 (2007/10/02)
The conjugate addition of Grignard reagents RMgX to α,β-unsaturated ketones and esters is effectively catalyzed by soluble copper ate-complexes of the type CuX3Li2, e.g.CuI*2LiCl.In the presence of Me3SiCl the corresponding ketone enolsilanes are formed in high yield and selectivity.Diastereoselectivity in the case of chiral ketones is similar to that observed by using stoichiometric amounts of cuprates R2CuLi.Thus CuX3Li2-catalyzed 1,4-additions of Grignard reagents may be an industrially viable process.Keywords: Copper; Magnesium; Lithium; Silicon; Ketone; Enolsilanes
Acyl Radical Cyclization in Synthesis. Part 4. Tandem Processes: The 7-endo/5-exo Serial Cyclization Approach to Enantiomerically Pure Bicyclodecan-2-ones
Batty, Duncan,Crich, David
, p. 3193 - 3204 (2007/10/02)
Two diastereoisomeric phenylselenoesters of 4,5-dihydroxyhept-6-enoic acid were prepared as their acetonide derivatives from the chiral pool.On treatment with tributyltin hydride and azoisobutyronitrile the erythro isomer cyclized to give meso-4,5-dihydroxycycloheptanone, as its acetonide, in moderate yield whereas under the same conditions the threo-isomer gave a much lower yield of the corresponding C2-symmetric ketone.In the erythro-series an alkyl group at C-7 of the heptenoyl system was found to retard significantly the direct endo-mode cyclisation; however, the cycloheptanone could still be obtained by a rearrangement when the tin hydride concentration was kept to a minimum.A tandem 7-endo/5-exo cyclization system was then constructed and tested, resulting in the formation of all four possible diastereoisomeric biyclodecanones.Further model studies were conducted on the effect of alkyl and alkoxy substituents at C-5 of the heptenoyl radical system on the mode of cyclisation.Alkyl substituents exert a steric effect whilst alkoxy substituents also have a stereoelectronic effect.
SYNTHESIS OF (+/-)-α-CHAMIGRENE
Plamondon, Josee,Canonne, Persephone
, p. 589 - 592 (2007/10/02)
Regiospecific spiroalkylation of the selectively generated enolate arising from the 1,4-addition of lithium dimethylcuprate to 3-methylcyclohex-2-en-1-one allows an efficient preparation of spiroketones, including a key intermediate for the synthesis of (+/-)-α-Chamigrene.
