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| Title: | 1,6-Aza-Michael addition of para-quinone methides with N-heterocycles catalyzed by Zn(OTf)2: A regioselective approach to N-diarylmethyl-substituted heterocycles |
| Authors: | Guin, Soumitra Saha, Hemonta K. Patel, Ashvani K. Gudimella, Santosh K. Biswas, Subhankar Samanta, Sampak |
| Keywords: | 2,6 di tert butyl 4 [(1 methyl 1h indol 3 yl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(2 chlorophenyl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(2 hydroxyphenyl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(2,5 dimethoxyphenyl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(3 methyl 1h pyrazol 1 yl)(phenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(2,5 dimethoxyphenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(2,5 hydroxyyphenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(4 fluorophenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(4 methoxyphenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(4 methylphenyl)methyl]phenol;2,6 di tert butyl 4 [(3,6 dibromo 9h carbazol 9 yl)(phenyl)methyl]phenol;2,6 di tert butyl 4 [(4 chlorophenyl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(4 chlorophenyl)(3,6 dibromo 9h carbazol 9 yl)methyl]phenol;2,6 di tert butyl 4 [(4 fluorophenyl)(1h pyrazol 1 yl)methyl]phenol;2,6 di tert butyl 4 [(4 methoxyphenyl)(1h pyrazol 1 yl) methyl]phenol;2,6 di tert butyl 4 [phenyl(1h pyrazol 1 yl)methyl]phenol;4 [(1h pyrazol 1 yl)(4 methylphenyl)methyl] 2,6 di tertbutylphenol;4 [(3 bromo 9h carbazol 9 yl)(4 chlorophenyl)methyl] 2,6 di tert butylphenol;4 [(4 bromo 1h pyrazol 1 yl)(phenyl)methyl] 2,6 di tert butylphenol;4 [(9h carbazol 9 yl)(2 thiophenyl)methyl] 2,6 dimethylphenol;4 [(9h carbazol 9 yl)(2,5 dimethoxyphenyl)methyl] 2,6 dimethylphenol;4 [(9h carbazol 9 yl)(4 chlorophenyl)methyl] 2,6 di tert butylphenol;4 [(9h carbazol 9 yl)(4 fluorophenyl)methyl] 2,6 di tert butylphenol;4 [(9h carbazol 9 yl)(4 methylphenyl)methyl] 2,6 di tert butylphenol;4 [(9h carbazol 9 yl)(phenyl)methyl] 2,6 di methylphenol;4 [(9h carbazol 9 yl)(phenyl)methyl] 2,6 di tert butylphenol;4 [anthracen 9 yl(1h pyrazol 1 yl)methyl] 2,6 di tertbutylphenol;heterocyclic compound;unclassified drug;unindexed drug;zinc derivative;Article;carbon nuclear magnetic resonance;chemical analysis;chemical bond;chemical structure;Michael addition;physical chemistry;physical parameters;priority journal;process optimization;proton nuclear magnetic resonance;regioselectivity;synthesis |
| Issue Date: | 2020 |
| Publisher: | Elsevier Ltd |
| Citation: | Guin, S., Saha, H. K., Patel, A. K., Gudimella, S. K., Biswas, S., & Samanta, S. (2020). 1,6-aza-michael addition of para-quinone methides with N-heterocycles catalyzed by zn(OTf)2: A regioselective approach to N-diarylmethyl-substituted heterocycles. Tetrahedron, 76(28-29) doi:10.1016/j.tet.2020.131338 |
| Abstract: | An efficient Zn(OTf)2-catalyzed regioselective C–N bond making reaction between a bunch of aryl/heteroaryl-substituted para-quinone methides as ideal 1,6-acceptors and various aromatic/non-aromatic aza-heterocycles bearing N–H moiety namely carbazoles, pyrazoles, indazole, benzotriazole and saccharin is reported. This 1,6-aza-Michael technique delivers predominantly N1-diarylmethyl-substituted heterocyclic scaffolds bearing a valuable phenolic moiety in good to high yields with an excellent regioselectivity. Furthermore, this LUMO lowering catalytic system allows different kinds of useful functionalities and excels with broad substrates under mild conditions. Importantly, our control experiments suggested that N2-adducts of indazole, benzotriazole and 3-methyl pyrazole as minor isomers were progressively converted into N1-adducts during the reaction via a retro-aza-Michael reaction triggered by Zn(OTf)2, offering excellent regioselectivities of the products. © 2020 Elsevier Ltd |
| URI: | https://doi.org/10.1016/j.tet.2020.131338 https://dspace.iiti.ac.in/handle/123456789/8791 |
| ISSN: | 0040-4020 |
| Type of Material: | Journal Article |
| Appears in Collections: | Department of Chemistry |
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