Formation of monocyclic and bicyclic aza-.beta.-lactams and other novel heterocycles from 1-(diphenylmethylene)-3-oxo-1,2-diazetidinium inner salt

Taylor, Edward C.; Clemens, Robert J.; Davies, Huw M. L.; Haley, Neil F.

doi:10.1021/ja00415a046

Cited by 30 publications

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“…The precipitated product was filtered and washed with H 2 O (2 × 10 mL) and hexane (2 × 10 mL). Yield 925 mg (88%); colorless crystals; mp 201−204 °C (EtOH); 1 H NMR (600 MHz, CDCl 3 ): δ = 7.17 (d, J = 8.5 Hz, 1H; Ar−H), 7.14 (d, J = 8.5 Hz, 1H; Ar−H), 5.93 (q, J = 6.9 Hz, 1H; 4-H), 3.95 (s, 3H; OCH 3 ), 2.67 (s, 3H; OC− CH 3 ), 2.13 (s, 3H; OC−CH 3 ), 1.40 (d, J = 6.9 Hz, 3H; 4-CH 3 ); 13 The Journal of Organic Chemistry 2,2,. A mixture of 8-chloro-4-methyl-3,4dihydro-2H-1,2,3-benzothiadiazine 1,1-dioxide (6d, 6.37 g, 27.4 mmol) and acetic anhydride (41 mL) was refluxed at 140 °C under stirring for 17 h. Then it was poured onto ice water (50 g).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The precipitated product was filtered and washed with H 2 O (3 × 40 mL). Yield 7.76 g (90%); colorless crystals; mp 171−173 °C (EtOH); 1 H NMR (600 MHz, CDCl 3 ): δ = 7.52 2H;7.22 (dd,J = 7.3,1.7 Hz,1H; Ar−H), 6.00 (q, J = 7.1 Hz, 1H; 4-H), 2.67 (s, 3H; OC−CH 3 ), 2.13 (s, 3H; OC−CH 3 ), 1.44 (d,J = 7.1 Hz,3H; ); 13 2,3-Diacetyl-4-methyl-3,4-dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxide (7f). A mixture of 4-methyl-3,4-dihydro-2H-1,2,3benzothiadiazine 1,1-dioxide (6f, 1.86 g, 9.4 mmol) and acetic anhydride (15 mL) was refluxed at 140 °C under stirring for 24 h. Then it was quenched with EtOH (20 mL), evaporated in vacuo, crystallized from hexane (15 mL), filtered and washed with H 2 O (10 mL) and EtOH (5 mL).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…A mixture of 4-methyl-3,4-dihydro-2H-1,2,3benzothiadiazine 1,1-dioxide (6f, 1.86 g, 9.4 mmol) and acetic anhydride (15 mL) was refluxed at 140 °C under stirring for 24 h. Then it was quenched with EtOH (20 mL), evaporated in vacuo, crystallized from hexane (15 mL), filtered and washed with H 2 O (10 mL) and EtOH (5 mL). Yield 2.32 g (87%); colorless crystals; mp 155−157 °C (EtOH); 1 H NMR (600 MHz, CDCl 3 ): δ = 7.89 (d, J = 7.7 Hz, 1H; Ar−H), 7.61 (td, J = 7.7, 1.3 Hz, 1H; Ar−H), 7.49 (t, J = 7.7 Hz, 1H; Ar−H), 7.31 (d, J = 7.7 Hz, 1H; Ar−H), 6.04 (q, J = 7.1 Hz, 1H; 4-H), 2.64 (s, 3H; OC−CH 3 ), 2.14 (s, 3H; OC−CH 3 ), 1.44 (d, J = 7.1 Hz, 3H; 4-CH 3 ); 13 Synthesis of 2,3-Disubstituted Benzothiadiazine Dioxides (1). 3-Acetyl-7,8-dichloro-2-ethyl-4-methyl-3,4-dihydro-2H-1,2,3benzothiadiazine 1,1-Dioxide (1c).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The precipitated product was filtered. Yield 620 mg (92%); colorless crystals; mp 146−147 °C (EtOH); 1 H NMR (600 MHz, [D 6 ]DMSO): δ = 8.00 (d, J = 8.7 Hz, 1H; 6-H), 7.69 (d, J = 8.7 Hz, 1H; 5-H), 5.69 (q, J = 7.0 Hz, 1H; 4-H), 3.84 (dq, 1H, J = 13.9, 7.1 Hz; N−CH), 3.22 (dq, 1H, J = 13.9, 7.1 Hz; N−CH), 2.22 (s, 3H; OC−CH 3 ), 1.67 (d, J = 7.0 Hz, 4-CH 3 ), 1.28 (t, J = 7.1 Hz, 3H, CH 2 −CH 3 ); 13 3-Acetyl-2-benzyl-7,8-dichloro-4-methyl-3,4-dihydro-2H-1,2,3benzothiadiazine 1,1-Dioxide (1d). To a suspension of t-BuOK (449 mg, 4.0 mmol) in DMF (4 mL) was added a solution of 7a (702 mg, 2.0 mmol) in DMF (8 mL) at room temperature.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…6 Hz,1H;7.29 (d,J = 8.6 Hz,1H;6.65 (dd,J = 54.8,51.6 Hz,1H; CHF 2 ), 5.62 (q, J = 7. 2 Hz,1H;3.28 (s,3H; ), 1.82 (d,J = 7.2 Hz,3H; ); 13 3-Acetyl-7-chloro-2,4-dimethyl-3,4-dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxide (1k). To a mixture of 7b (1.58 g, 5.0 mmol) and DMF (10 mL) was added t-BuOK (1.12 g, 10.0 mmol) and DMF (20 mL) at room temperature.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Basicity-Tuned Reactivity: diaza-[1,2]-Wittig versus diaza-[1,3]-Wittig Rearrangements of 3,4-Dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxides

et al. 2020

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The base-induced ( t -BuOK) rearrangement reactions of 3,4-dihydro-2 H -1,2,3-benzothiadiazine 1,1-dioxides result in a ring opening along the N–N bond, followed by ring closure with the formation of new C–N bonds. The position of the newly formed C–N bond can selectively be tuned by the amount of the base, providing access to new, pharmacologically interesting ring systems with high yield. While with 2 equiv of t -BuOK 1,2-benzisothiazoles can be obtained in a diaza -[1,2]-Wittig reaction, with 6 equiv of the base 1,2-benzothiazine 1,1-dioxides can be prepared in most cases as the main product, in a diaza -[1,3]-Wittig reaction. DFT calculations and detailed NMR studies clarified the mechanism, with a mono- or dianionic key intermediate, depending on the amount of the reactant base. Also, the role of an enamide intermediate formed during the workup of the highly basic (6 equiv of base) reaction was clarified. The substrate scope of the reaction was also explored in detail.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 3 more Smart Citations

Basicity-Tuned Reactivity: diaza-[1,2]-Wittig versus diaza-[1,3]-Wittig Rearrangements of 3,4-Dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxides

et al. 2020

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[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

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In spite of their late discovery in the middle of 20 th century, the importance of azomethine imines and their [3+2] cycloaddition reactions has grown constantly throughout the decades. Today, [3+2] cycloadditions of azomethine imines have become indispensable in the preparation of pyrazole derivatives with all degrees of saturation. The structural diversity of azomethine imines is wide and comprises acyclic, C , N ‐cyclic, N , N ‐cyclic, and C , N , N ‐cyclic 1,3‐dipoles. Although electron‐deficient dipolarophiles are preferred, electron‐rich dipolarophiles, such as enol ethers and enamines, are also commonly used in these reactions. Compared to cyclocondensation methods and [3+2] cycloadditions with diazoalkanes and nitrile imines, [3+2] cycloadditions with azomethine imines provide access to a greater diversity of pyrazole derivatives with all degrees of saturation. As with other 1,3‐dipolar cycloadditions, a concerted and nearly synchronous mechanism has been proposed for most [3+2] cycloadditions of azomethine imines, although a stepwise mechanism may be viable in some cases. Several examples of asymmetric [3+2] cycloadditions of azomethine imines that afford non‐racemic cycloadducts with high enantioselectivity have been reported. These asymmetric cycloadditions are performed with various types of transition metal catalysts and organocatalysts, and indicate their potential for the asymmetric synthesis of saturated pyrazole derivatives. Finally, many examples of copper‐catalyzed and thermal, strain‐promoted [3+2] cycloadditions of azomethine imines (in particular sydnones) clearly indicate wide applicability of these reactions in bioconjugation, fluorescent labelling, materials functionalization, and other applications outside the realm of pure organic synthesis.

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Synthesis of Four‐Membered Aza‐Heterocycles through Catalytic [2 + 2] Cycloaddition Reactions Assisted by Metal Complexes

Prieto

2020

Synthetic Approaches to Nonaromatic Nitrogen Heterocycles

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Formation of monocyclic and bicyclic aza-.beta.-lactams and other novel heterocycles from 1-(diphenylmethylene)-3-oxo-1,2-diazetidinium inner salt

Cited by 30 publications

References 0 publications

Basicity-Tuned Reactivity: diaza-[1,2]-Wittig versus diaza-[1,3]-Wittig Rearrangements of 3,4-Dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxides

Basicity-Tuned Reactivity: diaza-[1,2]-Wittig versus diaza-[1,3]-Wittig Rearrangements of 3,4-Dihydro-2H-1,2,3-benzothiadiazine 1,1-Dioxides

[3 + 2] Cycloadditions of Azomethine Imines

Synthesis of Four‐Membered Aza‐Heterocycles through Catalytic [2 + 2] Cycloaddition Reactions Assisted by Metal Complexes

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