1504-67-2Relevant academic research and scientific papers
Ternary Catalysis Enabled Three-Component Asymmetric Allylic Alkylation as a Concise Track to Chiral α,α-Disubstituted Ketones
Chang, Wenju,Fu, Xiang,Hu, Wenhao,Kang, Zhenghui,Liang, Yong,Tian, Xue,Xu, Xinfang,Zhao, Wenxuan
, p. 20818 - 20827 (2021/12/17)
Multicomponent reactions that involve interception of onium ylides through Aldol, Mannich, and Michael addition with corresponding bench-stable acceptors have demonstrated broad applications in synthetic chemistry. However, because of the high reactivity and transient survival of these in situ generated intermediates, the substitution-type interception process, especially the asymmetric catalytic version, remains hitherto unknown. Herein, a three-component asymmetric allylation of α-diazo carbonyl compounds with alcohols and allyl carbonates is disclosed by employing a ternary cooperative catalysis of achiral Pd-complex, Rh2(OAc)4, and chiral phosphoric acid CPA. This method represents the first example of three-component asymmetric allylic alkylation through an SN1-type trapping process, which involves a convergent assembly of two active intermediates, Pd-allyl species, and enol derived from onium ylides, providing an expeditious access to chiral α,α-disubstituted ketones in good to high yields with high to excellent enantioselectivity. Combined experimental and computational studies have shed light on the mechanism of this novel three-component reaction, including the critical role of Xantphos ligand and the origin of enantioselectivity.
Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols
Shi, Chang-Yun,Yin, Liang,Zhang, Qi,Zhou, Si-Wei
supporting information, p. 26351 - 26356 (2021/11/09)
By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.
Highly pH-Dependent Chemoselective Transfer Hydrogenation of α,β-Unsaturated Aldehydes in Water
Luo, Nianhua,Liao, Jianhua,Ouyang, Lu,Wen, Huiling,Liu, Jitian,Tang, Weiping,Luo, Renshi
, p. 3025 - 3031 (2019/08/30)
The pH-dependent selective Ir-catalyzed hydrogenation of α,β-unsaturated aldehydes was realized in water. Using HCOOH as the hydride donor at low pH, the unsaturated alcohol products were obtained exclusively, while the saturated alcohol products were formed preferentially by employing HCOONa as the hydride donor at high pH. A wide range of functional groups including electron-rich as well as electron-poor substituents on the aryl group of α,β-unsaturated aldehydes can be tolerated, affording the corresponding products in excellent yields with high TOF values. High selectivity and yields were also observed for α,β-unsaturated aldehydes with aliphatic substituents. Our mechanistic investigations indicate that the pH value is critical to the chemoselectivity.
Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
, p. 9589 - 9593 (2019/12/02)
We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
Rhodium-Catalyzed Synthesis of α,β-Unsaturated Ketones through Sequential C-C Coupling and Redox Isomerization
Li, Hong-Shuang,Guo, Guili,Zhang, Rui-Ze,Li, Fei
supporting information, p. 5040 - 5043 (2018/08/24)
A novel Rh(I)-catalyzed sequential C-C coupling and redox isomerization between allylic alcohols and 1,3-dienes has been accomplished. This versatile protocol provides expeditious access to a broad range of polysubstituted α,β-unsaturated ketones with excellent atom economy and regioselectivity.
Stereoselective and Site-Specific Allylic Alkylation of Amino Acids and Small Peptides via a Pd/Cu Dual Catalysis
Huo, Xiaohong,He, Rui,Fu, Jingke,Zhang, Jiacheng,Yang, Guoqiang,Zhang, Wanbin
supporting information, p. 9819 - 9822 (2017/08/02)
We report a stereoselective and site-specific allylic alkylation of Schiff base activated amino acids and small peptides via a Pd/Cu dual catalysis. A range of noncoded α,α-dialkyl α-amino acids were easily synthesized in high yields and with excellent enantioselectivities (up to >99% ee). Furthermore, a direct and highly stereoselective synthesis of small peptides with enantiopure α-alkyl or α,α-dialkyl α-amino acids residues incorporated at specific sites was accomplished using this dual catalyst system.
Highly selective transfer hydrogenation of α,β-unsaturated carbonyl compounds using Cu-based nanocatalysts
Siddqui, Nazia,Sarkar, Bipul,Pendem, Chandrashekar,Khatun, Rubina,Sivakumar Konthala,Sasaki, Takehiko,Bordoloi, Ankur,Bal, Rajaram
, p. 2828 - 2837 (2017/07/15)
Simultaneous dehydrogenation of cyclohexanol to cyclohexanone and hydrogenation of α,β-unsaturated carbonyl compounds to corresponding α,β-unsaturated alcohols was carried out in a single pot reaction without addition of any external hydrogen donor. Cu nanoclusters supported on nanocrystalline MgO were found to be the active catalyst for the chemoselective transfer hydrogenation of unsaturated carbonyl compounds to produce the corresponding alcohols with very high yields. Transfer hydrogenation of cyclohexanol and cinnamaldehyde produced cyclohexanone and cinnamyl alcohol with 100% selectivity. This Cu/MgO catalyst can be easily recovered and recycled up to more than five times without any significant loss of activity, which confirmed the true heterogeneous nature of this catalyst. Several α,β-unsaturated compounds were also tested for this reaction and it was found that for all the cases the yield is >95%. The ease of handling without requiring high pressure H2 or a hazardous hydrogen source makes this transfer hydrogenation more practical and useful.
Multifunctional novel Diallyl disulfide (DADS) derivatives with β-amyloid-reducing, cholinergic, antioxidant and metal chelating properties for the treatment of Alzheimer's disease
Manral, Apra,Saini, Vikas,Meena, Poonam,Tiwari, Manisha
, p. 6389 - 6403 (2015/10/05)
A series of novel Diallyl disulfide (DADS) derivatives were designed, synthesized and evaluated as chemical agents, which target and modulate multiple facets of Alzheimer's disease (AD). The results showed that the target compounds 5a-l and 7e-m exhibited significant anti-Aβ aggregation activity, considerable acetylcholinesterase (AChE) inhibition, high selectivity towards AChE over butyrylcholinesterase (BuChE), potential antioxidant and metal chelating activities. Specifically, compounds 7k and 7l exhibited highest potency towards self-induced Aβ aggregation (74% and 71.4%, 25 μM) and metal chelating ability. Furthermore, compounds 7k and 7l disaggregated Aβ fibrils generated by Cu2+-induced Aβ aggregation by 80.9% and 78.5%, later confirmed by transmission electron microscope (TEM) analysis. Besides, 7k and 7l had the strongest AChE inhibitory activity with IC50 values of 0.056 μM and 0.121 μM, respectively. Furthermore, molecular modelling studies showed that these compounds were capable of binding simultaneously to catalytic active site (CAS) and peripheral anionic site (PAS) of AChE. All the target compounds displayed moderate to excellent antioxidant activity with ORAC-FL values in the range 0.546-5.86 Trolox equivalents. In addition, absorption, distribution, metabolism and excretion (ADME) profile and toxicity prediction (TOPKAT) of best compounds 7k and 7l revealed that they have drug like properties and possess very low toxic effects. Collectively, the results strongly support our assertion that these compounds could provide good templates for developing new multifunctional agents for AD treatment.
AMINE COMPOUND AND PHARMACEUTICAL USE THEREOF
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Page/Page column 173, (2010/04/25)
Provided is a novel amine compound represented by the following formula (I) having a superior peripheral blood lymphocyte decreasing action and superior in the immunosuppressive action, rejection suppressive action and the like, which shows decreased side effects of, for example, bradycardia and the like, or a pharmaceutically acceptable acid addition salt thereof, or a hydrate thereof, or a solvate thereof. wherein each symbol is as defined in the specification.
Synthesis of oxadiazole-2-oxide analogues as potential antischistosomal agents
Rai, Ganesha,Thomas, Craig J.,Leister, William,Maloney, David J.
supporting information; experimental part, p. 1710 - 1713 (2009/07/05)
The synthesis of several 1,2,5-oxadiazole-2-oxide (Furoxan) analogues is described herein. These compounds were prepared in an effort to probe the SAR around the phenyl substituent and oxadiazole core for our studies toward thioredoxin-glutathione reductase (TGR) inhibition and antischistosomal activity.
