4912-92-9Relevant academic research and scientific papers
Palladium-catalyzed carbon - Carbon bond-forming 1,2-ligand migration of organoalanes
Fillion, Eric,Carson, Rebekah J.,Trepanier, Vincent E.,Goll, Julie M.,Remorova, Anna A.
, p. 15354 - 15355 (2004)
A one-pot, two-step process that transforms terminal alkynes into ethyl methyl-substituted benzylic quaternary carbon centers is described. (E)-2,2-Disubstituted-1-alkenyldimethylalanes have been shown to participate in 1,2-alkyl migration from aluminum to carbon with concomitant arylation at the 2-position to furnish ethyl methyl-substituted benzylic quaternary carbon centers, when reacted intramolecularly with aryl halides and triflates in the presence of a Pd(0) catalyst. The protocol is initiated with Cp2ZrCl2-catalyzed methylalumination of terminal alkynes followed by palladium-catalyzed intramolecular arylation of the resulting (E)-2,2-disubstituted-1-alkenyldimethylalanes, leading to 1,2-methyl shift from aluminum to carbon. In that sequence, a total of three new C-C single bonds are made, and two of the three alkyl groups on Me3Al transferred to the substrate on vicinal carbons. This method was applied to a variety of substrates, and the mechanism was investigated by deuterium-labeling experiments, which revealed that protodealumination of the final dialkylaluminum triflate or halide intermediates by CH3CN results in the formation of the fourth bond in the course of the transformation. Copyright
Experimental and computational study of the intramolecular reactivity of free tert-butylphenylmethylene. Modification of the chemistry of tert-butylmethylene by the introduction of a phenyl group
Armstrong, Brian M.,McKee, Michael L.,Shevlin, Philip B.
, p. 7408 - 7412 (1998)
The chemistry of ferf-butylphenylmethylene, 2, has been investigated experimentally and computationally. Free carbene 2 was generated by the thermal rearrangement of p-ter-butylphenyl-methylene and observed to rearrange by C-H insertion to give 1,1-dimethyl-2-phenylcyclopropane, 3, and by C-C insertion to yield 2-methyl-3-phenyl-2-butene, 4. An examination of the 3:4 ratio led to the conclusion that C-H insertion is favored over C-C insertion by 1.6 ± 0.1 kcal/mol in good agreement with a calculated (PMP2/6-31G(d)//MP2/6-31G(d)+ZPC/6-31(d)) value of 2.0 kcal/ mol. The S-T gap in 2 is estimated to be 5-6 kcal/mol.
Ni-catalysed reductive arylalkylation of unactivated alkenes
Jin, Youxiang,Wang, Chuan
, p. 1780 - 1785 (2019)
In this protocol Ni-catalysed reductive arylalkylation of unactivated alkenes tethered to aryl bromides with primary alkyl bromides has been accomplished, providing a new path to construct diverse benzene-fused carbo- and heterocyclic cores including inda
Nickel-Catalyzed Asymmetric Reductive Arylbenzylation of Unactivated Alkenes
Jin, Youxiang,Yang, Haobo,Wang, Chuan
supporting information, p. 2724 - 2729 (2020/04/02)
Herein, we report a nickel-catalyzed asymmetric two-component reductive dicarbofunctionalization of aryl iodide-tethered unactivated alkenes using benzyl chlorides as the challenging coupling partner. This arylbenzylation reaction enables the efficient synthesis of diverse benzene-fused cyclic compounds bearing a quaternary stereocenter with a high tolerance of sensitive functionalities in highly enantioselective manner. The preliminary mechanistic investigations suggest a radical chain reaction mechanism.
Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
supporting information, p. 2328 - 2332 (2020/01/08)
Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
Nickel-Catalyzed Reductive Arylalkylation via a Migratory Insertion/Decarboxylative Cross-Coupling Cascade
Jin, Youxiang,Yang, Haobo,Wang, Chuan
supporting information, p. 7602 - 7608 (2019/10/02)
Reported is a nickel-catalyzed reductive arylalkylation of unactivated alkenes tethered to aryl iodides with redox active N-hydroxyphthalimide esters as the alkyl source through successful merging of migratory insertion and decarboxylative cross-coupling in a cascade. This new method avoids the use of pregenerated organometallic reagents and thus enables the synthesis of diverse benzene-fused carbo- and heterocyclic compounds with high tolerance of a wide range of functional groups.
Nickel-catalyzed asymmetric intramolecular reductive heck reaction of unactivated alkenes
Yang, Feiyan,Jin, Youxiang,Wang, Chuan
, p. 6989 - 6994 (2019/09/30)
An asymmetric Ni-catalyzed intramolecular reductive Heck reaction of unactivated alkenes tethered to aryl bromides has been accomplished, providing a variety of benzene-fused cyclic compounds bearing a quaternary stereogenic center in good to excellent yi
Palladium-Catalyzed Alkylation with Alkyl Halides by C(sp3)?H Activation
Wu, Zhuo,Ma, Ding,Zhou, Bo,Ji, Xiaoming,Ma, Xiaotian,Wang, Xiaoling,Zhang, Yanghui
supporting information, p. 12288 - 12291 (2017/09/06)
Utilizing halogens as traceless directing goups represents an attractive strategy for C?H functionalization. A two C?H alkylation system, initiated by the oxidative addition of organohalides to Pd0, has been developed. The first reaction involves an intermolecular alkylation of palladacycles to form C(sp3)?C(sp2) bonds followed by C(sp2)?H activation/cyclization to deliver alkylated benzocyclobutenes as the final products. In the second reaction, two C?C bonds are formed by the reaction of palladacycles with CH2Br2, and provides a facile and efficient method for the synthesis of indanes. The alkylated benzocyclobutene products can be transformed into tricyclic hyrocarbons, and the indane derivatives are essential structural motifs in bioactive and odorant molecules.
Amines vs. N-Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1-Methylimidazole N-Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols
Murray, James I.,Spivey, Alan C.
, p. 3825 - 3830 (2016/01/25)
A comparison of the relative catalytic efficiencies of Lewis-basic amines vs. N-oxides for the acylation, sulfonylation and silylation of primary, secondary and tertiary alcohols is reported. Whilst the amines are generally superior to the N-oxides for acylation, the N-oxides are superior for sulfonylation and silylation. In particular, 1-methylimidazole N-oxide (NMI-O) is found to be a highly efficient catalyst for sulfonylation and silylation reactions. To the best of our knowledge, NMI-O is the first amine or N-oxide Lewis basic organocatalyst capable of promoting the efficient silylation of tert-alcohols in high yield with low catalyst loading under mild reaction conditions.
Mode attack of atomic carbon on benzene rings
Armstrong, Brian M.
, p. 6007 - 6011 (2007/10/03)
Reaction of are generated carbon atoms with tert-butylbenzene, 4, gives 3-methyl-3-phenyl-1-butene, 5, and 1,1-dimethylindane, 6. Labeling studies and isotope effects demonstrate that 5 results from an insertion into a methyl C-H bond followed by 1,2 hydrogen shift while 6 arises from initial ortho C-H insertion followed by intramolecular insertion into a methyl C-H bend. When fluoroboric acid is added to the 77 K matrix of 4 + C, tert-butyltropylium fluoroborate, 18, is formed. Labeling studies indicate that 18 results from initial insertion of C into meta and para C-H bonds of 4 followed by ring expansion to cycloheptatetraenes which are subsequently protonated. The reaction of C with benzene gives similar results, indicating that initial C-H insertion is the preferred mode of attack of atomic carbon on benzene rings.
