1608-27-1Relevant academic research and scientific papers
Development and Mechanistic Investigations of Enantioselective Pd-Catalyzed Intermolecular Hydroaminations of Internal Dienes
Park, Sangjune,Malcolmson, Steven J.
, p. 8468 - 8476 (2018)
We report the development of highly enantio- and regioselective Pd-catalyzed intermolecular hydroaminations of challenging 1,4-disubstituted acyclic dienes. Several aryl/alkyl-disubstituted dienes and a sterically differentiated alkyl/alkyl-disubstituted diene undergo coupling with a variety of secondary aliphatic amines, indoline, and primary anilines to generate allylic amines with myriad α-alkyl groups in up to 78% yield, >98:2 rr, and 98.5:1.5 er. A number of experiments, including deuterium labeling and transamination studies, shed light on mechanistic details of the reaction, such as the reversibility of individual steps of the proposed catalytic cycle and of the reaction as a whole.
A new route to cyclopentenones via ruthenium-catalyzed carbonylative cyclization of allylic carbonates with alkenes
Morisaki, Yasuhiro,Kondo, Teruyuki,Mitsudo, Take-Aki
, p. 949 - 952 (2000)
(equation presented) [RuCl2(CO)3]2/Et3N and (η3-C3H5)RuBr(CO)3/Et 3N are highly effective catalyst systems for carbonylative cyclization of allylic carbonates with alkenes to give the corresponding cyclopentenones in high yields. For example, treatment of allyl methyl carbonate (1a) with 2-norbornene (2a) in the presence of a catalytic amount of [RuCl2(CO)3]2 (2.5 mol %) and Et3N (10 mol %) at 120 °C for 5 h under 3 atm of carbon monoxide gave the corresponding cyclopentenone, exo-4-methyltricyclo[5.2.1.02,6]dec.4.en-3-one (3a), in 80% yield with high stereoselectivity (exo 100%).
Investigation of bicyclic thioketones as triggers for liquid crystal optical switches
Bradford, Rochelle Fisher,Schuster, Gary B.
, p. 1075 - 1080 (2003)
The axially chiral bicyclic thioketones 11 and 15 were prepared and investigated for suitability as chiroptical triggers in a liquid crystal optical switch. Irradiation of partially resolved 15 with unpolarized light leads to its conversion to the racemic form (photoracemization). However, irradiation of racemic thioketones 11 and 15 with circularly polarized light does not lead to detectable photoresolution. The lack of photoresolution was traced to inefficiency in intramolecular, throughbond triplet energy transfer. These thioketones are not suitable for use as phototriggers.
Palladium-catalyzed coupling reactions of functionalized styryl bromides with 1-propenyltributyltin
Zapata, Antonio J.,Ruiz, Jacqueline
, p. C6 - C8 (1994)
The palladium-catalyzed coupling reaction of 1-propenyltributyltin with functionalized styryl bromides is described. 1,3-Dienes are obtained in low to moderate yields except with β,β-dibromostyrene.The latter undergoes a novel organotin-promoted dehydrobromination-coupling sequence to give a 1,3-enyne as final product.Key words: Tin; Palladium; Styryl bromide; Coupling reaction; Bromides; Catalysis
Synthesis of renewable alkylated naphthalenes with benzaldehyde and angelica lactone
Cong, Yu,Li, Guangyi,Li, Ning,Wang, Aiqin,Wang, Ran,Wang, Xiaodong,Xu, Jilei,Zhang, Tao
supporting information, p. 5474 - 5480 (2021/08/16)
Herein, we report a new route for the synthesis of renewable alkylated naphthalenes (ANs) with benzaldehyde and angelica lactone, two platform compounds that can be derived from lignocellulose.
Ni-Catalyzed Regioselective Hydroarylation of 1-Aryl-1,3-Butadienes with Aryl Halides
Wang, Chengdong,Guo, Yingjie,Wang, Xiaoming,Wang, Zheng,Ding, Kuiling
supporting information, p. 15903 - 15907 (2021/10/07)
An efficient nickel-catalyzed regioselective hydroarylation of 1,3-dienes with aryl halides and a silane has been developed, affording a range of allylic arenes in good to excellent yields under mild conditions. This method exhibits broad substrate scope,
Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
Liu, Bingxue,Liu, Qiang,Liu, Xufang
supporting information, p. 6750 - 6755 (2020/03/13)
Migratory functionalization of alkenes has emerged as a powerful strategy to achieve functionalization at a distal position to the original reactive site on a hydrocarbon chain. However, an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminal alkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminal alkynes and cobalt-catalyzed hydrogenation of either 2-alkynes or conjugated diene intermediates. Notably, this practical non-noble metal catalytic system enables efficient control of the chemo-, regio-, and stereoselectivity of this transformation.
Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
supporting information, p. 18223 - 18230 (2020/12/04)
The catalytic isomerization of C-C double bonds is an indispensable chemical transformation used to deliver higher-value analogues and has important utility in the chemical industry. Notwithstanding the advances reported in this field, there is compelling demand for a general catalytic solution that enables precise control of the C═C bond migration position, in both cyclic and acyclic systems, to furnish disubstituted and trisubstituted alkenes. Here, we show that catalytic amounts of an appropriate earth-abundant iron-based complex, a base and a boryl compound, promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from one substrate can be facilitated, isomeric olefin mixtures commonly found in petroleum-derived feedstock can be transformed to a single alkene product, and unsaturated moieties embedded within linear and heterocyclic biologically active entities can be obtained.
Palladium-Catalyzed Regio- A nd Enantioselective Hydrosulfonylation of 1,3-Dienes with Sulfinic Acids: Scope, Mechanism, and Origin of Selectivity
Dong, Dongfang,Zhang, Qinglong,Zi, Weiwei
supporting information, p. 15860 - 15869 (2020/10/18)
Chiral sulfones are important structural motifs in organic synthesis because of their widespread use in pharmaceutical chemistry. In particular, chiral allylic sulfones have drawn particular interest because of their synthetic utility. However, enantioselective synthesis of 1,3-disubstituted unsymmetrical chiral allylic sulfones remains a challenge. In this article, we report a protocol for (R)-DTBM-Segphos/Pd-catalyzed regio- A nd enantioselective hydrosulfonylation of 1,3-dienes with sulfinic acids, which provides atom- A nd step-economical access to 1,3-disubstituted chiral allylic sulfones. The reaction occurs under mild conditions and has a broad substrate scope. Combined experimental and computational studies suggest that the reaction is initiated by a ligand-to-ligand hydrogen transfer followed by a C-S bond reductive elimination via a six-membered transition state. Steric repulsion between the olefinic C-H of the substrate and the tert-butyl group of (R)-DTBM-Segphos was found to be a key factor in the enantiocontrol.
Mild Isomerization of Conjugated Dienes Using Co-Mediated Hydrogen Atom Transfer
Delgado, Kyle R.,Youmans, Dustin D.,Diver, Steven T.
supporting information, p. 750 - 754 (2020/01/31)
A mild and high yielding rearrangement of 1,3-disubstituted-1,3-dienes to 1,1,4-trisubstituted-1,3-dienes using a cobaloxime catalyst and a silane cocatalyst is reported. Chiral centers near the conjugated diene were not racemized. Deuterium labeling studies are consistent with a hydrogen atom transfer mechanism, and radical intermediates were found to be accessible due to the observed ring opening of a cyclopropane ring.
