1940-19-8Relevant academic research and scientific papers
Alkyne gem-Hydrogenation: Formation of Pianostool Ruthenium Carbene Complexes and Analysis of Their Chemical Character
Biberger, Tobias,Gordon, Christopher P.,Leutzsch, Markus,Peil, Sebastian,Guthertz, Alexandre,Copéret, Christophe,Fürstner, Alois
, p. 8845 - 8850 (2019)
Parahydrogen (p-H2) induced polarization (PHIP) NMR spectroscopy showed that [CpXRu] complexes with greatly different electronic properties invariably engage propargyl alcohol derivatives into gem-hydrogenation with formation of pianostool ruthenium carbenes; in so doing, less electron rich CpX rings lower the barriers, stabilize the resulting complexes and hence provide opportunities for harnessing genuine carbene reactivity. The chemical character of the resulting ruthenium complexes was studied by DFT-assisted analysis of the chemical shift tensors determined by solid-state 13C NMR spectroscopy. The combined experimental and computational data draw the portrait of a family of ruthenium carbenes that amalgamate purely electrophilic behavior with characteristics more befitting metathesis-active Grubbs-type catalysts.
A Novel Synthesis of Homologated Allylic Alcohols Using Dimethylsulphonium Methylide
Harnett, J. J.,Alcaraz, L.,Mioskowski, C.,Martel, J. P.,Gall, T. Le,et al.
, p. 2009 - 2012 (1994)
The reaction of excess dimethylsulphonium methylide with various aliphatic and aromatic ketones leads exclusively to homologated allylic alcohols in good yields.
Allylic Alcohols by Methylene Transfer from N-Lithiomethyl-N,N',N'',N''-tetramethyldiethylenetriamine to Epoxides
Schakel, Marius,Luitjes, Hendrikus,Dewever, Frank L. M.,Scheele, Jan,Klumpp, Gerhard W.
, p. 513 - 514 (1995)
Allylic (homoallylic) alcohols are obtained from epoxides (and certain oxetanes) and N-lithiomethyl-N,N',N'',N''-tetramethyldiethylenetriamine.
Antiandrogenic, maspin induction, and antiprostate cancer activities of tanshinone IIA and its novel derivatives with modification in ring A
Liu, Weiguo,Zhou, Jinming,Geng, Guoyan,Shi, Qingwen,Sauriol, Francoise,Wu, Jian Hui
, p. 971 - 975 (2012)
Expression of metastatic suppressor maspin is lost in advanced prostate cancer. Clinically relevant mutations in androgen receptor (AR) convert antiandrogens into AR agonists, promoting prostate tumor growth. We discovered tanshinone IIA (TS-IIA) is a potent antagonist of mutated ARs and induces maspin expression through AR. TS-IIA suppressed AR expression and induced apoptosis in LNCaP cells. Syntheses of TS-IIA derivatives (1-9) revealed that the 4,4-dimethyl group at ring A is important for TS-IIA's antiandrogenic and maspin induction activities.
High Reactivity of Strained Seven-Membered-Ring trans-Alkenes
Sanzone, Jillian R.,Woerpel
, p. 790 - 793 (2016)
trans-Oxasilacycloheptenes are highly reactive strained alkenes. Competition reactions showed that these seven-membered ring trans-alkenes underwent [4+2] cycloaddition reactions faster than a trans-cyclooctene. They also reacted with quinones and dimethyl acetylenedicarboxylate to form adducts with high diastereoselectivity. Kinetic studies showed that ring strain increases nucleophilicity by approximately 109. trans-Oxasilacycloheptenes are strained seven-membered-ring trans-alkenes that underwent [4+2] cycloaddition reactions faster than a bicyclic trans-cyclooctene. They also reacted with quinones and dimethyl acetylenedicarboxylate to form adducts with high diastereoselectivity. Kinetic studies showed that ring strain increases nucleophilicity by approximately 109.
Photochemical Organocatalytic Regio- and Enantioselective Conjugate Addition of Allyl Groups to Enals
Berger, Martin,Carboni, Davide,Melchiorre, Paolo
supporting information, p. 26373 - 26377 (2021/11/16)
We report the first catalytic enantioselective conjugate addition of allyl groups to α,β-unsaturated aldehydes. The chemistry exploits the visible-light-excitation of chiral iminium ions to activate allyl silanes towards the formation of allylic radicals, which are then intercepted stereoselectively. The underlying radical mechanism of this process overcomes the poor regio- and chemoselectivity that traditionally affects the conjugate allylation of enals proceeding via polar pathways. We also demonstrate how this organocatalytic strategy could selectively install a valuable prenyl fragment at the β-carbon of enals.
Oxidation Under Reductive Conditions: From Benzylic Ethers to Acetals with Perfect Atom-Economy by Titanocene(III) Catalysis
Funk, Pierre,Richrath, Ruben B.,Bohle, Fabian,Grimme, Stefan,Gans?uer, Andreas
supporting information, p. 5482 - 5488 (2021/02/03)
Described here is a titanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines, respectively, with pendant epoxides. The reaction proceeds by catalysis in single-electron steps. The oxidative addition comprises an epoxide opening. An H-atom transfer, to generate a benzylic radical, serves as a radical translocation step, and an organometallic oxygen rebound as a reductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate. An interesting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions.
NiH-Catalyzed Proximal-Selective Hydroamination of Unactivated Alkenes
Jeon, Jinwon,Lee, Changseok,Seo, Huiyeong,Hong, Sungwoo
supporting information, p. 20470 - 20480 (2020/11/27)
Reported herein is a modular, NiH-catalyzed system capable of proximal-selective hydroamination of unactivated alkenes with diverse amine sources. The key to the successful implementation of this approach is the promotion of NiH insertion into even highly substituted olefins via coordination of the bidentate directing group to the nickel complex. A wide range of primary and secondary amines can be installed in both internal and terminal unactivated alkenes with excellent regiocontrol under the optimized reaction conditions. This protocol is flexible and general for the preparation of a variety of valuable β- and γ-amino acid building blocks that would otherwise be difficult to synthesize. The utility of this transformation was further demonstrated by the site-selective late-stage modification of complex and medicinally relevant molecules. Combined experimental and computational studies illuminate the detailed reaction mechanism.
Sustainable Palladium-Catalyzed Tsuji-Trost Reactions Enabled by Aqueous Micellar Catalysis
Braga, Felipe C.,Gallou, Fabrice,Lee, Nicholas R.,Lippincott, Daniel J.,Lipshutz, Bruce H.,Moghadam, Farbod A.,Zhu, Bingchun
supporting information, (2020/07/15)
Palladium-catalyzed allylic substitution, or "Tsuji-Trost"reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.
Synthesis method of 2-(1-cyclohexenyl) ethylamine
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Paragraph 0041-0043, (2020/11/02)
The invention belongs to the technical field of organic chemistry, and particularly relates to a synthesis method of a compound 2-(1-cyclohexenyl) ethylamine (I). Cyclohexanone (II) and a Grignard reagent are subjected to a Grignard reaction in an organic solvent to be converted into 1-vinyl cyclohexanol (III), the 1-vinyl cyclohexanol (III) and a chlorination reagent are subjected to a chlorination/rearrangement one-pot reaction in an organic solvent in the presence of organic alkali to prepare (2-chloroethylene methylene) cyclohexane (IV), the (2-chloroethylene methylene) cyclohexane (IV) and urotropine are subjected to quaternization in an organic solvent to form N-cyclohexylidene ethyl urotropine hydrochloride (V), and finally, hydrolysis rearrangement is carried out in a solvent in the presence of inorganic mineral acid to obtain the 2-(1-cyclohexenyl) ethylamine (I). The compound (I) has important industrial application value as an intermediate for synthesizing the antitussive drug dextromethorphan hydrobromide. The method has the advantages of cheap and accessible raw materials, mild reaction conditions, high yield and high product purity, is simple to operate, and is convenient for industrial production.
