28795-94-0Relevant academic research and scientific papers
Catalyst-Controlled 1,2- and 1,1-Arylboration of α-Alkyl Alkenyl Arenes
Bergmann, Allison M.,Dorn, Stanna K.,Smith, Kevin B.,Logan, Kaitlyn M.,Brown, M. Kevin
, p. 1719 - 1723 (2019)
Two methods are reported for the 1,2- and 1,1-arylboration of α-methyl vinyl arenes. In the case of 1,2-arylboration, the formation of a quaternary center occurred through a rare cross-coupling reaction of a tertiary organometallic complex. 1,1-Arylboration was enabled by catalyst optimization and occurred through a β-hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations.
Iridium-catalyzed synthesis of β-methylated secondary alcohols using methanol
Liu, Shiyuan,Lu, Yao,Song, Ao,Wang, Mingchun,Wang, Rongzhou,Xing, Ling-Bao
, p. 90 - 96 (2022/02/14)
A general synthesis of β-methylated secondary alcohols via tandem α-methylation/transfer hydrogenation from non-methylated ketones with methanol by a Cp*Ir complex [Cp*Ir(2,2′-bpyO)(OH)]Na with a bipyridine-based functional ligand was reported. Remarkably, β-methylated secondary alcohols can be obtained under milder reaction conditions using methanol as the methylating agent (C1 source) by employing this catalytic system. A wide range of structurally diverse ketones bearing different functional groups was methylated and hydrogenated with excellent toleration in fair to high yields. This method provides a readily available and highly efficient route to β-methylated secondary alcohols using methanol.
Tertiary alkylations of aldehydes, ketones or imines using benzylic organoboronates and a base catalyst
Nagao, Kazunori,Nakamura, Kei,Ohmiya, Hirohisa,Sato, Yukiya,Yabushita, Kenya
supporting information, p. 1065 - 1069 (2020/11/09)
The KHMDS-catalyzed tertiary alkylation of aldehydes, ketones or imines using tertiary benzylic organoboronates is reported. This protocol permitted the use of tertiary benzylic alkylboronates as the tertiary alkyl anion for construction of highly congested contiguous sp3 carbon centers. The mild and transition-metal-free reaction conditions are attractive features of the protocol.
Nickel-Copper-Catalyzed Hydroacylation of Vinylarenes with Acyl Fluorides and Hydrosilanes
Ueda, Yusuke,Iwai, Tomohiro,Sawamura, Masaya
supporting information, p. 9410 - 9414 (2019/05/29)
The hydroacylation of vinylarenes with acyl fluorides and hydrosilanes was enabled by a synergistic bimetallic Ni/Cu-catalytic system, giving access to the corresponding branched ketone products. The reaction takes place under mild conditions at 25–80 °C and tolerates base-sensitive functional groups such as methoxycarbonyl and acetoxy groups.
Nickel Catalyzed Intermolecular Carbonyl Addition of Aryl Halide
Ishida, Seima,Suzuki, Hiroyuki,Uchida, Seiichiro,Yamaguchi, Eiji,Itoh, Akichika
supporting information, p. 7483 - 7487 (2019/12/11)
In this study, we develop a nickel-catalyzed carbonyl arylation reaction employing aldehydes with aryl and allyl halides. Various aryl, α,β-unsaturated aldehyde and aliphatic aldehydes can be converted into their corresponding secondary alcohols in moderate-to-high yields. In addition, we extended this approach to develop an asymmetric reductive coupling reaction that combines nickel salts with chiral bisoxazoline ligands to give secondary alcohols with moderate enantioselectivity.
Photocatalytic Barbier reaction-visible-light induced allylation and benzylation of aldehydes and ketones
Berger, Anna Lucia,Donabauer, Karsten,K?nig, Burkhard
, p. 7230 - 7235 (2018/10/02)
We report a photocatalytic version of the Barbier type reaction using readily available allyl or benzyl bromides and aromatic aldehydes or ketones as starting materials to generate allylic or benzylic alcohols. The reaction proceeds at room temperature under visible light irradiation with the organic dye 3,7-di(4-biphenyl)1-naphthalene-10-phenoxazine as a photocatalyst and DIPEA as sacrificial electron donor. The proposed cross-coupling mechanism of a ketyl- and an allyl or benzyl radical is supported by spectroscopic investigations and cyclic voltammetry measurements.
Chemoselective Benzylation of Aldehydes Using Lewis Base Activated Boronate Nucleophiles
Hollerbach, Michael R.,Barker, Timothy J.
supporting information, p. 1425 - 1427 (2018/05/24)
A benzylation of aldehydes using primary and secondary benzylboronic acid pinacol esters is reported. Activation of the boronic ester with s-butyllithium rendered it nucleophilic toward aldehydes. The activated nucleophile chemoselectively transfers the benzyl group over the sec-butyl group, providing excellent yields of the benzylated products. 11B NMR experiments were performed to study the mechanism of this transformation.
Enantioselective CuH-Catalyzed Reductive Coupling of Aryl Alkenes and Activated Carboxylic Acids
Bandar, Jeffrey S.,Ascic, Erhad,Buchwald, Stephen L.
supporting information, p. 5821 - 5824 (2016/06/09)
A new method for the enantioselective reductive coupling of aryl alkenes with activated carboxylic acid derivatives via copper hydride catalysis is described. Dual catalytic cycles are proposed, with a relatively fast enantioselective hydroacylation cycle followed by a slower diastereoselective ketone reduction cycle. Symmetrical aryl carboxyclic anhydrides provide access to enantioenriched α-substituted ketones or alcohols with excellent stereoselectivity and functional group tolerance.
Rhodium-catalysed tandem hydroformylation/arylation reaction with boronic acids
Almeida, Ana R.,Dias, Roberto D.,Monteiro, Carlos J. P.,Abreu, Artur R.,Gois, Pedro M. P.,Bayon, J. Carles,Pereira, Mariette M.
supporting information, p. 1223 - 1228 (2014/05/06)
A new efficient multicatalytic process involving a single catalyst to promote tandem hydroformylation/arylation reactions is disclosed. The effect of the rhodium ligand was evaluated and the rhodium/triphenylphosphine catalytic system was selected to apply the methodology to different olefins and boronic acids. High yields (up to 89%) and good to excellent isomer ratios (up to 98:2) were achieved using aryl olefins as starting materials. This new methodology allows the preparation of secondary alcohols, from simple olefins, and paves the way for the synthesis of high-value products, namely vinylindole and anethole derivatives.
Role of free space and conformational control on photoproduct selectivity of optically pure α-alkyldeoxybenzoins within a water-soluble organic capsule
Kulasekharan, Revathy,Maddipatla, Murthy V. S. N.,Parthasarathy, Anand,Ramamurthy
, p. 942 - 949 (2013/04/10)
Optically pure α-alkyl deoxybenzoins resulting in products of Norrish Type I and Type II reactions upon excitation has been investigated within the octa acid (OA) capsule in water. The product distribution was different from that in an organic solvent and was also dependent on the length of the α-alkyl chain. Most importantly, a rearrangement product not formed in an organic solvent arising from the triplet radical pair generated by Norrish Type I reaction was formed, and its yield was dependent on the alkyl chain length. In an organic solvent, since the cage lifetime is shorter than the time required for intersystem crossing (ISC) of the triplet radical pair to the singlet radical pair the recombination with or without rearrangement of the primary radical pair (phenylacetyl and benzyl) does not occur. Recombination without rearrangement within the capsule as inferred from monitoring the racemization of the optically pure α-alkyl deoxybenzoins suggesting the capsule's stability for at least 10-8 s (the time required for ISC) is consistent with our previous photophysical studies that showed partial opening and closing of the capsule in the time range of microseconds.
