769-59-5Relevant articles and documents
Visible-Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones
Laktsevich-Iskryk, Marharyta V.,Varabyeva, Nastassia A.,Kazlova, Volha V.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.,Hurski, Alaksiej L.
, p. 2431 - 2434 (2020/04/20)
Isomerization to linear ketones is a valuable transformation of 1,2-disubstituted cyclopropanols proceeding through radical intermediates. Despite simplicity of this reaction, the known protocol required stoichiometric amounts of both an oxidant and a reducing agent. In this article, we report a catalytic isomerization of 1,2-disubstituted cyclopropanols to linear ketones enabled by the photoredox catalytic system consisting of an acridinium photocatalyst and diphenyl disulfide under irradiation with blue LEDs.
Tandem Acid/Pd-Catalyzed Reductive Rearrangement of Glycol Derivatives
Ciszek, Benjamin,Fleischer, Ivana,Kathe, Prasad,Schmidt, Tanno A.
, p. 3641 - 3646 (2020/03/25)
Herein, we describe the acid/Pd-tandem-catalyzed transformation of glycol derivatives into terminal formic esters. Mechanistic investigations show that the substrate undergoes rearrangement to an aldehyde under [1,2] hydrogen migration and cleavage of an oxygen-based leaving group. The leaving group is trapped as its formic ester, and the aldehyde is reduced and subsequently esterified to a formate. Whereas the rearrangement to the aldehyde is catalyzed by sulfonic acids, the reduction step requires a unique catalyst system comprising a PdII or Pd0 precursor in loadings as low as 0.75 mol % and α,α′-bis(di-tert-butylphosphino)-o-xylene as ligand. The reduction step makes use of formic acid as an easy-to-handle transfer reductant. The substrate scope of the transformation encompasses both aromatic and aliphatic substrates and a variety of leaving groups.
Oxidation of Nonactivated Anilines to Generate N-Aryl Nitrenoids
Deng, Tianning,Mazumdar, Wrickban,Ford, Russell L.,Jana, Navendu,Izar, Ragda,Wink, Donald J.,Driver, Tom G.
, p. 4456 - 4463 (2020/03/05)
A low-temperature, protecting-group-free oxidation of 2-substituted anilines has been developed to generate an electrophilic N-aryl nitrenoid intermediate that can engage in C-NAr bond formation to construct functionalized N-heterocycles. The exposure of 2-substituted anilines to PIFA and trifluoroacetic acid or 10 mol percent Sc(OTf)3 triggers nitrenoid formation, followed by productive and selective C-NAr and C-C bond formation to yield spirocyclic- or bicyclic 3H-indoles or benzazepinones. Our experiments demonstrate the breadth of these oxidative processes, uncover underlying fundamental elements that control selectivity, and demonstrate how the distinct reactivity patterns embedded in N-aryl nitrenoid reactive intermediates can enable access to functionalized 3H-indoles or benzazepinones.
I(III)-catalyzed oxidative cyclization - Migration tandem reactions of unactivated anilines
Deng, Tianning,Shi, Emily,Thomas, Elana,Driver, Tom G.
, p. 9102 - 9106 (2020/11/13)
An I(III)-catalyzed oxidative cyclization-migration tandem reaction using Selectfluor as the oxidant was developed that converts unactivated anilines into 3H-indoles is reported herein. The reaction requires as little as 1 mol % of the iodocatalyst and is mild, tolerating pyridine and thiophene functional groups, and the dependence of the diastereoselectivity of the process on the identity of the iodoarene or iodoalkane precatalyst suggests that the catalyst is present for the stereochemical determining C-N bond forming step.
Proline-promoted dehydroxylation of α-ketols
Mostinski, Yelena,Lankri, David,Konovalov, Yana,Nataf, Riva,Tsvelikhovsky, Dmitry
, p. 9345 - 9350 (2019/10/22)
A new single-step proline-potassium acetate promoted reductive dehydroxylation of α-ketols is reported. We introduce the unexplored reactivity of proline and, for the first time, reveal its ability to function as a reducing agent. The developed metal-free and open-flask operation generally results in good yields. Our protocol allows the challenging selective dehydroxylation of hydroxyketones without affecting other functional groups.
Two efficient pathways for the synthesis of aryl ketones catalyzed by phosphorus-free palladium catalysts
Wirwis,Feder-Kubis,Trzeciak
, p. 61 - 72 (2018/01/05)
Allylic alcohols, 1-buten-3-ol, 1-penten-3-ol and 1-octen-3-ol, reacted with aryl iodides (iodotoluene, 4-iodotoluene, 4-iodophenol and 4-iodanisole) under Heck reaction conditions to form corresponding saturated aryl ketones in one step. The same products were obtained in a two-step tandem reaction consisted of the Heck coupling of allylic alcohols with aryl iodides, followed by hydrogenation. Reactions were catalyzed by phosphorus-free palladium precursors modified with the menthol-substituted imidazolium chlorides. Formation of crystalline palladium nanoparticles, of the diameter up to 65 nm, in the reaction mixture was evidenced by TEM.
Catalytic Radical-Polar Crossover Reactions of Allylic Alcohols
Touney, Eric E.,Foy, Nicholas J.,Pronin, Sergey V.
supporting information, p. 16982 - 16987 (2018/12/14)
Radical-polar crossover hydrofunctionalizations of tertiary allylic alcohols are described. Depending on the structure of the catalyst, corresponding epoxides or semipinacol rearrangement products are selectively obtained in good yields. Experimental evidence points to the participation of alkylcobalt complexes as electrophilic intermediates.
Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach
Polidano, Kurt,Allen, Benjamin D. W.,Williams, Jonathan M. J.,Morrill, Louis C.
, p. 6440 - 6445 (2018/07/25)
A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs a Kn?lker-type (cyclopentadienone)iron carbonyl complex as catalyst (2 mol %) and exhibits a broad reaction scope. A variety of ketones, indoles, oxindoles, amines, and sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).
Utilization of MeOH as a C1 Building Block in Tandem Three-Component Coupling Reaction
Chakrabarti, Kaushik,Maji, Milan,Panja, Dibyajyoti,Paul, Bhaskar,Shee, Sujan,Das, Gourab Kanti,Kundu, Sabuj
supporting information, p. 4750 - 4753 (2017/09/22)
Ru(II) catalyzed tandem synthesis of α-branched methylated ketones via multicomponent reactions following the hydrogen borrowing process is described. This nonphosphine-based air and moisture stable catalyst efficiently produced various methylated ketones using methanol as a methylating agent. This system was found to be highly effective in three-component coupling between methanol, primary alcohols, and methyl ketones. A proposed catalytic cycle for the α-methylation is supported by DFT calculations as well as kinetic experiments.
Regioselective 1,2-Diol Rearrangement by Controlling the Loading of BF3·Et2O and Its Application to the Synthesis of Related Nor-Sesquiterene- and Sesquiterene-Type Marine Natural Products
Wang, Jun-Li,Li, Hui-Jing,Wang, Hong-Shuang,Wu, Yan-Chao
, p. 3811 - 3814 (2017/07/26)
The regiocontrolled rearrangement of 1,2-diols has been achieved by controlling the loading of BF3·Et2O. Its applicability is showcased by the divergent synthesis of austrodoral, austrodoric acid, and 8-epi-11-nordriman-9-one, as well as a formal synthesis of siphonodictyal B and liphagal. A new light is shed on piancol-type rearrangements that will be useful in diversity-oriented synthesis of related natural products.
