21567-68-0Relevant academic research and scientific papers
Chemo- and Regioselective Isomerization of Epoxides to Carbonyl Compounds via Palladium Catalysis
Kulasegaram, Sanjitha,Kulawiec, Robert J.
, p. 7195 - 7196 (1994)
Palladium(0)-tertiary phosphine complexes catalyze the chemo- and regioselective isomerization of epoxides to carbonyl compounds in good to excellent yields; alkyl-substituted epoxides afford methyl ketones, and aryl-substituted epoxides form aldehydes or ketones via cleavage of the benzylic C-O bond.
On the mechanism of the palladium(0)-catalyzed isomerization of epoxides to carbonyl compounds
Kulasegaram, Sanjitha,Kulawiec, Robert J.
, p. 1361 - 1374 (1998)
The isomerization of trans-3-methyl-2-(2-naphthyl)oxirane to 2-naphthylpropanone by Pd(OAc)2/PBu3 in C6H6 is first order in both epoxide and in palladium catalyst, with activation parameters of ΔH = 12.5 kcal/mol and ΔS = -35.7 e.u. A comparison of the isomerization rates of trans-3-methyl-2-(2-naphthyl)oxirane and trans-3-deuterio-3-methyl-2-(2-naphthyl)oxirane reveals a kinetic isotope effect (k(H)/k(D)) of 1.01 (± 0.09). The reaction rates in benzene and acetonitrile are very similar; however, changing from benzene to a hydrogen bond-donating solvent (t-BuOH) increases the reaction rate substantially. These observations are consistent with a mechanism involving: (1) turnover-limiting S(N)2 attack of Pd(0) at the benzylic position of the epoxide; (b) rapid β-hydride elimination to form a Pd(II) hydrido-enolate complex; and (c) fast reductive elimination to afford the ketone, with concomitant regeneration of the Pd(0) catalyst.
Involvement of the Baeyer-Villiger Monooxygenase IfnQ in the Biosynthesis of Isofuranonaphthoquinone Scaffold of JBIR-76 and -77
Katsuyama, Yohei,Sone, Kaoru,Satou, Ryutaro,Izumikawa, Miho,Takagi, Motoki,Fujie, Manabu,Satoh, Noriyuki,Shin-Ya, Kazuo,Ohnishi, Yasuo
, p. 1021 - 1028 (2016)
JBIR-76 and -77 are isofuranonaphthoquinones (IFNQs) isolated from Streptomyces sp. RI-77. Draft genome sequencing and gene disruption analysis of Streptomyces sp. RI-77 showed that a type II polyketide synthase (PKS) gene cluster (ifn cluster) was responsible for the biosynthesis of JBIR-76 and -77. It was envisaged that an octaketide intermediate (C16) could be synthesized by the minimal PKS (IfnANO) and that formation of the IFNQ scaffold (C13) would therefore require a C-C bond cleavage reaction. An ifnQ disruptant accumulated some shunt products (C15), which were presumably produced by spontaneous cyclization of the decarboxylated octaketide intermediate. Recombinant IfnQ catalyzed the Baeyer-Villiger oxidation of 1-(2-naphthyl)acetone, an analogue of the bicyclic octaketide intermediate. Based on these results, we propose a pathway for the biosynthesis of JBIR-76 and -77, involving IfnQ-catalyzed C-C bond cleavage as a key step in the formation of the IFNQ scaffold. JBIR-76 and -77 are isofuranonaphthoquinones isolated from Streptomyces sp. RI-77. We have identified the JBIR-76 and -77 biosynthesis gene cluster (ifn cluster) and elucidated the critical role of the Baeyer-Villiger monooxygenase IfnQ in the construction of the isofuranonaphthoquinone scaffold.
Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
He, Qianwen,Zhang, Dong,Zhang, Fengcai,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 6961 - 6966 (2021/09/11)
An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
Gold-Catalyzed [3+2]-Annulations of α-Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
Chen, Ching-Nung,Cheng, Wei-Min,Wang, Jian-Kai,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
supporting information, p. 4479 - 4484 (2021/01/21)
This work reports gold-catalyzed [3+2]-annulations of α-diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3-dihydrofurans with high regio- and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]-annulations with α-diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral forms of gold and phosphoric acid. Our mechanistic analysis supports that cyclopentadienes serve as nucleophiles to attack gold carbenes at the more substituted alkenes, yielding gold enolates that complex with chiral phosphoric acid to enhance the enantioselectivity.
Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
supporting information, p. 1778 - 1781 (2020/03/11)
A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
Nickel-Catalyzed Mono-Selective α-Arylation of Acetone with Aryl Chlorides and Phenol Derivatives
Amgoune, Abderrahmane,Derhamine, Sary Abou,Krachko, Tetiana,Monteiro, Nuno,Pilet, Guillaume,Schranck, Johannes,Tlili, Anis
supporting information, p. 18948 - 18953 (2020/09/01)
The challenging nickel-catalyzed mono-α-arylation of acetone with aryl chlorides, pivalates, and carbamates has been achieved for the first time. A nickel/Josiphos-based catalytic system is shown to feature unique catalytic behavior, allowing the highly selective formation of the desired mono-α-arylated acetone. The developed methodology was applied to a variety of (hetero)aryl chlorides including biologically relevant derivatives. The methodology has been extended to the unprecedented coupling of acetone with phenol derivatives. Mechanistic studies allowed the isolation and characterization of key Ni0 and NiII catalytic intermediates. The Josiphos ligand is shown to play a key role in the stabilization of NiII intermediates to allow a Ni0/NiII catalytic pathway. Mechanistic understanding was then leveraged to improve the protocol using an air-stable NiII pre-catalyst.
COMPOSITIONS AND METHODS OF REGULATING CANCER RELATED DISORDERS AND DISEASES
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, (2017/08/01)
Provided herein are naphthylic derivative compounds, or pharmaceutically acceptable salts thereof, that are useful for inhibiting cancers. Also provided herein are methods of using effective amounts of said compounds, optionally with pharmaceutical carrie
Enantioselective synthesis of β-substituted chiral allylic amines: Via Rh-catalyzed asymmetric hydrogenation
Wang, Qingli,Gao, Wenchao,Lv, Hui,Zhang, Xumu
supporting information, p. 11850 - 11853 (2016/10/07)
An asymmetric mono-hydrogenation of 2-acetamido-1,3-dienes catalyzed by a Rh-DuanPhos complex has been developed. This approach provides easy access to chiral allylic amines with excellent enantioselectivities and high regioselectivities. The products are valuable chiral building blocks for pharmaceuticals.
Preparation of a highly congested carbazoyl-derived p,n-type phosphine ligand for acetone monoarylations
Fu, Wai Chung,Zhou, Zhongyuan,Kwong, Fuk Yee
, p. 1553 - 1558 (2016/06/09)
We report a newly developed carbazoyl-derived P,N-type phosphine ligand (L1) for the monoarylation of acetone with aryl chlorides. The proposed Pd(dba)2/L1 catalyst exhibited remarkable catalytic reactivity toward highly electron rich and sterically congested aryl chlorides, with catalyst loading as low as 0.1 mol % of Pd along with excellent chemoselectivity. A reaction rate study of the system using electronically diverse aryl chlorides determined the mechanisms regarding the rate-limiting steps in this reaction. The oxidative addition adduct of Pd-PhenCar-Phos with p-chlorotoluene showed the participation of N-Pd coordination in the metal complex. The isolated palladium complex C1 could be utilized as a precatalyst in the transformation and achieved performance comparable to that of the in situ generated palladium species.
