888071-72-5Relevant academic research and scientific papers
Direct Access for the Regio- And Stereoselective Synthesis of N-Alkenylpyrazoles and Chromenopyrazoles
Kurma, Siva Hariprasad,Sridhar, Balasubramanian,Bhimapaka, China Raju
supporting information, p. 2271 - 2282 (2021/02/06)
A highly regio- and stereoselective method was developed for the preparation of N-alkenylpyrazoles and chromenopyrazoles by the reaction of N-tosylhydrazones and salicyl N-tosylhydrazones with alkynes under neat conditions in the presence of La(OTf)3. The present study was found to be efficient and convenient for direct access to N-alkenylpyrazoles and chromenopyrazoles through C-C, C-N, and C-O bond forming reactions. Structure assignment of N-alkenylpyrazole compound 5c was confirmed by X-ray analysis.
AgOTf-catalyzed reaction of sulfonyl hydrazones with ynamides led to stereoselective synthesis of α-amino alkenyl-substituted hydrazone derivatives
Cao, Ziping,Yan, Shikun,Zhao, Changyin,Sun, Xuejun,Tian, Laijin,Meng, Xin
, (2019/08/27)
A novel method for the synthesis of α-amino alkenyl-substituted hydrazone derivatives was disclosed through silver-catalyzed reaction of sulfonyl hydrazones with ynamides. The present method features mild conditions, high stereoselectivity and good yields. The proposed mechanism involves silver-mediated generation of a keteniminium ion intermediate to facilitate the stereoselective addition of hydrazones in the presence of K2CO3, while pyrazole ring could not be constructed under the current conditions.
Biological evaluation of p-toluene sulphonylhydrazone as carbonic anhydrase IX inhibitors: An approach to fight hypoxia-induced tumors
Queen, Aarfa,Khan, Parvez,Idrees, Danish,Azam, Amir,Hassan, Md. Imtaiyaz
, p. 840 - 850 (2017/10/06)
To find potential inhibitors of human carbonic anhydrase IX (CAIX), we have successfully deigned, synthesized and characterized three p-toluene sulphonylhydrazone derivatives (1–3). Molecular docking studies provided the structural basis of CAIX inhibition and a deeper insight into the protein-ligand interactions. p-Toluene sulphonylhydrazone derivatives show a well organized conformational compatibility with the active site of CAIX. The protein-ligand complex was stabilized by several non-covalent interactions offered by residues present in the active site cavity. The actual binding affinity of synthesized compounds with CAIX was experimentally measured by fluorescence and isothermal titration calorimetry (ITC). Results of both fluorescence binding and ITC measurements show the binding affinity of p-Toluene sulphonylhydrazone derivatives to the CAIX in the μM range. CAIX enzyme inhibition assay showed the IC50 values in nM range. Though all the three compounds (1–3) showed a good binding with CAIX, compound 2 showed the best inhibition of CAIX activity. These compounds were non-toxic on normal cell lines (HEK-293) and significantly inhibit the proliferation of hypoxic cancer cells. All compounds induce apoptosis in the hypoxic cancer cells. These compounds may be further exploited as promising therapeutic agents to control the hypoxia-induced tumors.
Hypervalent iodine (III)-mediated oxidation of aryl sulfonylhydrazones: A facile synthesis of N-aroyl-N′-acyl arylsulfonylhydrazides
Ramakrishna,Dev, Kapil,Maurya, Saransh Wales,Siddiqui, Ibadur Rahman,Maurya, Rakesh
supporting information, p. 570 - 573 (2017/01/16)
We have developed a novel and efficient method for the oxidation of aryl sulfonylhydrazones to N-aroyl-N′-acyl arylsulfonylhydrazides, using hypervalent iodine (III) reagent in good yields at room temperature.
Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig Olefinations
Aggarwal, Varinder K.,Fulton, J. Robin,Sheldon, Chris G.,De Vicente, Javier
, p. 6034 - 6035 (2007/10/03)
Tosylhydrazones derived from aryl aldehydes react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity. These reactions occur through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides, with the water-soluble trimethyl phosphate as the byproduct. Similar reactions can also be performed using ethyl diazoacetate; however, high E selectivity was only observed in the presence of LiBr. In this case, the reaction is believed to occur via the phosphonate anion, formed through an Arbuzov reaction. Thus this olefination reaction occurs through a Horner-Wadsworth-Emmons (HWE) reaction but the phosphonate anion is generated under completely base-free conditions. Copyright
A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities
Aggarwal, Varinder K.,Alonso, Emma,Bae, Imhyuck,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Patel, Mamta,Porcelloni, Marina,Richardson, Jeffery,Stenson, Rachel A.,Studley, John R.,Vasse, Jean-Luc,Winn, Caroline L.
, p. 10926 - 10940 (2007/10/03)
A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.
Diastereoselective Synthesis of Cyclopropane Amino Acids Using Diazo Compounds Generated in Situ
Adams, Luke A.,Aggarwal, Varinder K.,Bonnert, Roger V.,Bressel, Bettina,Cox, Russell J.,Shepherd, Jon,De Vicente, Javier,Walter, Magnus,Whittingham, William G.,Winn, Caroline L.
, p. 9433 - 9440 (2007/10/03)
A simple and high-yielding method for the preparation of cyclopropane amino acids is described. The novel method involves the one-pot cyclopropanation of readily available dehydroamino acids using aryl and unsaturated diazo compounds generated in situ fro
Catalytic cyclopropanation of alkenes using diazo compounds generated in situ. A novel route to 2-arylcyclopropylamines
Aggarwal, Varinder K.,De Vicente, Javier,Bonnert, Roger V.
, p. 2785 - 2788 (2007/10/03)
(Equation presented) A user-friendly, one-pot process for catalytic cyclopropanation of alkenes from tosylhydrazones is described. The cyclopropanation of N-vinylphthalimide provides a new route to 2-arylcyclopropylamines, and this is exemplified in the efficient synthesis of the HIV-1 reverse transcriptase inhibitor 6.
