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Synlett 2018; 29(07): 890-893
DOI: 10.1055/s-0036-1591908
DOI: 10.1055/s-0036-1591908
letter
The First Example of Azole-Fused Cyclic Anhydride Reacting in the Castagnoli–Cushman Way
This research was supported by the Russian Scientific Foundation (project grant 14-50-00069).Weitere Informationen
Publikationsverlauf
Received: 13. November 2017
Accepted after revision: 02. Januar 2018
Publikationsdatum:
27. Februar 2018 (online)
◊ On research training leave from National Polytechnic Institute of Industrial and Chemical Engineering, Toulouse, France.
Abstract
Pyrazole-fused cyclic anhydrides have been employed for the first time as the Castagnoli–Cushman reaction partners to produce hitherto unknown 4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-7-carboxylates in remarkably convenient and speedy fashion. Attempts to realize the same chemistry with indole and benzimidazole analogues failed.
Key words
multicomponent reactions - Castagnoli–Cushman reaction - nonstabilized enolate - pyrazole-fused - cyclic anhydridesSupporting Information
- Supporting information for this article is available online at https://doi.org/10.1055/s-0036-1591908.
- Supporting Information
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References and Notes
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- 8 General Procedure for the Synthesis of Compounds 13a–n A mixture of anhydride 12 (0.5 mmol) and the corresponding imine (0.52 mmol) in dry chlorobenzene (2 mL) was stirred in a screw-cap vial at 130 °C for 16 h. Upon cooling to r.t. the solvent was removed in vacuo, and the residue was dissolved in acetone (10 mL). To the solution were added K2CO3 (1 mmol) and MeI (1 mmol), and the mixture was vigorously stirred at r.t. for 20 h. The solution was separated from solids, evaporated, and the resulting residue was subjected to column chromatography on silica gel.
- 9 Characterization Data of Representative Compounds Compound 13a: colorless amorphous solid. 1H NMR (400 MHz, CDCl3): δ = 7.68 (d, J = 8.2 Hz, 2 H), 7.23 (s, 1 H), 7.21 (d, J = 7.9 Hz, 2 H), 7.13 (d, J = 8.1 Hz, 2 H), 7.06 (d, J = 8.2 Hz, 2 H), 5.28 (s, 1 H), 5.26 (d, J = 1.4 Hz, 1 H), 4.22 (dq, J = 14.4, 7.2 Hz, 1 H), 3.79 (s, 3 H), 2.89 (dq, J = 14.2, 7.1 Hz, 1 H), 2.37 (s, 3 H), 2.31 (s, 3 H), 1.17 (t, J = 7.2 Hz, 3 H). 13C NMR (101 MHz, CDCl3): δ = 168.5, 157.1, 153.0, 138.8, 138.2, 135.7, 133.7, 129.9, 129.4, 129.4, 126.0, 125.6, 104.7, 65.3, 61.7, 53.5, 40.1, 21.3, 21.0, 13.1. HRMS: m/z [M + H]+ calcd for C24H26N3O3: 404.1969; found: 404.1986. Compound 13i: colorless viscous oil. 1H NMR (400 MHz, CDCl3): δ = 7.36 (dd, J = 3.6, 1.1 Hz, 1 H), 7.25 (dd, J = 5.1, 1.1 Hz, 1 H), 7.15 (s, 1 H), 7.12 (d, J = 8.1 Hz, 2 H), 7.08–7.01 (m, 3 H), 5.27 (s, 1 H), 5.25 (d, J = 1.4 Hz, 1 H), 4.21 (dq, J = 14.4, 7.2 Hz, 1 H), 3.78 (s, 3 H), 2.87 (dq, J = 14.2, 7.1 Hz, 1 H), 2.29 (s, 3 H), 1.15 (t, J = 7.2 Hz, 3 H). 13C NMR (101 MHz, CDCl3): δ = 168.3, 156.8, 148.2, 138.8, 135.9, 135.2, 133.5, 129.9, 127.5, 125.9, 125.2, 124.7, 104.7, 65.2, 61.7, 53.5, 40.1, 21.0, 13.1. HRMS: m/z [M + H]+ calcd for C21H22N3O3S: 396.1376; found: 396.1379; Compound 13l: colorless viscous oil. 1H NMR (400 MHz, CDCl3): δ = 7.13 (d, J = 7.9 Hz, 2 H), 7.02 (d, J = 8.0 Hz, 2 H), 6.82 (s, 1 H), 5.20 (s, 1 H), 5.18 (s, 1 H), 4.13 (dt, J = 13.8, 7.9 Hz, 1 H), 3.77 (s, 3 H), 2.67 (ddd, J = 13.5, 8.2, 5.3 Hz, 1 H), 2.32 (s, 3 H), 1.65–1.46 (m, 2 H), 1.29 (s, 9 H), 0.89 (t, J = 7.4 Hz, 3 H). 13C NMR (101 MHz, CDCl3): δ = 168.8, 163.8, 157.7, 138.6, 134.9, 133.9, 129.8, 126.1, 104.7, 64.8, 61.9, 53.3, 46.5, 32.2, 30.4, 21.2, 21.0, 11.0. HRMS: m/z [M + H]+ calcd for C22H30N3O3: 384.2282; found: 384.2293.
- 10 Kantin G. Chupakhin E. Dar’in D. Krasavin M. Tetrahedron Lett. 2017; 58: 3160