Conjugated azoalkenes. Part XVI. Reaction of some conjugated azoalkenes with β-nitrocarbonyl derivatives.

Attanasi, Orazio A.; Ballini, Roberto; Liao, Zhiyuan; Santeusanio, Stefania; Serra-Zanetti, Franco

doi:10.1016/s0040-4020(01)87977-1

Cited by 14 publications

(9 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…13 C NMR (CDCl 3 , 100 MHz) δ 18.9, 52. 6,55.8,58.6,71.3,74.1,82.2,107.5,125.5,127.6,127.7,128.3,128.4,129.3,136.3,137.6,156.0,169.6. Anal.…”

Section: Methodsmentioning

confidence: 99%

“…13 C NMR (CDCl 3 , 75 MHz) δ 18. 6,52.6,55.0,55.8,58.3,71.4,74.1,82.4,107.9,127.7,127.8,128.4,137.7,162.0,169.6. Anal.…”

Section: General Procedures For the Thermal Cycloaddition Between Dds...mentioning

confidence: 99%

“…13 C NMR (CDCl 3 , 100 MHz) δ 18. 6,27.6,52.4,57.0,69.0,70.3,71.1,71.7,72.0,73.2,83.7,83.8,85.7,109.7,127.4,128.3,137.4,137.8,138.3,160.3,169.6. Anal.…”

Section: General Procedures For the Thermal Cycloaddition Between Dds...mentioning

confidence: 99%

“…1 H NMR (CDCl 3 , 400 MHz) δ 1.39 (s, 3H), 1.59 (s, 9H), 1.84-1.91 (m, 1H), 2.16-2.25 (m, 1H), 3.25-3.31(m, 1H), 3.47 (dt, 1H, J = 7.2, 12.5 Hz), 3.54 (d, 1H, J = 5.2), 3.77 (s, 3H), 3.85-3.88 (m, 1H), 4.30 (dd, 1H, 3 J = 2 6,. 5.4), 4.46 and 4.51 (AB system, 2H, J = 11.9 Hz), …”

mentioning

confidence: 99%

See 3 more Smart Citations

Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation

et al. 2014

Self Cite

View full text Add to dashboard Cite

Asymmetric 1,3-dipolar cycloadditions between 1,2-diaza-1,3-dienes and chiral non-racemic nitrones to give 3-substituted-5-diazenyl isoxazolidines were studied both experimentally and theoretically. Whereas cyclic nitrones provide complete selectivity for the cycloaddition reaction (only one isomer is obtained), acyclic nitrones derived from D-glyceraldehyde and D-galactose lead to 1 : 1 mixtures of two isomers. A DFT analysis based on reactivity indices correctly predicts the regiochemistry of the reaction in agreement with the high electron-withdrawing character of the diazenyl group. The same theoretical studies considering solvent effects (PCM model) based on transition state theory are in qualitative agreement with the observed experimental results.

show abstract

“…13 C NMR (CDCl 3 , 100 MHz) δ 18.9, 52. 6,55.8,58.6,71.3,74.1,82.2,107.5,125.5,127.6,127.7,128.3,128.4,129.3,136.3,137.6,156.0,169.6. Anal.…”

Section: Methodsmentioning

confidence: 99%

“…13 C NMR (CDCl 3 , 75 MHz) δ 18. 6,52.6,55.0,55.8,58.3,71.4,74.1,82.4,107.9,127.7,127.8,128.4,137.7,162.0,169.6. Anal.…”

Section: General Procedures For the Thermal Cycloaddition Between Dds...mentioning

confidence: 99%

“…13 C NMR (CDCl 3 , 100 MHz) δ 18. 6,27.6,52.4,57.0,69.0,70.3,71.1,71.7,72.0,73.2,83.7,83.8,85.7,109.7,127.4,128.3,137.4,137.8,138.3,160.3,169.6. Anal.…”

Section: General Procedures For the Thermal Cycloaddition Between Dds...mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…1,2 Azoalkenes can react as the dipolarophile (olefinic moiety) in [3 + 2] cycloaddition reactions [3][4][5] or as the three-center component (olefinic π-bond and the nonbonding electron pair at the adjacent nitrogen atom), thus resembling an isoelectronic hetero equivalent of the allyl anion. [6][7][8][9][10][11] Recently, we reported the reaction of conjugated phenylazoalkenes 4 (R 3 = H) and thiocyanic acid 12 giving rise to the formation of 1-anilino-2,3-dihydro-1H-imidazole-2-thiones 7 (Scheme 1). 13,14 This reaction is considered to be initiated by a [3+2] cycloaddition step forming cycloadduct 5.…”

mentioning

confidence: 99%

Tandem [3 + 2] Cycloaddition Reaction of Azo-alkenes and Thiocyanic Acid: Extending the Scope of the Classical "Criss-Cross" Cycloaddition Reaction

Schantl¹,

Nadenik²

1998

Synlett

View full text Add to dashboard Cite

Phenylazoalkenes 4 with full substitution at the terminal carbon atom react with thiocyanic acid affording 2,3,5,6,7,7a-hexahydro-3-phenyl-1H-imidazo [1,5-b][1,2,4]triazole-2,5-dithiones 8. The bicyclic compounds 8 result from two consecutive [3+2] cycloaddition steps, thus adding a novel facet to the classical "Crisscross" reaction.The heterodiene system of conjugated azoalkenes (1,2-diaza-1,3-butadienes) is capable of participating in various cycloaddition reactions. 1,2 Azoalkenes can react as the dipolarophile (olefinic moiety) in [3 + 2] cycloaddition reactions 3-5 or as the three-center component (olefinic π-bond and the nonbonding electron pair at the adjacent nitrogen atom), thus resembling an isoelectronic hetero equivalent of the allyl anion. [6][7][8][9][10][11] Recently, we reported the reaction of conjugated phenylazoalkenes 4 (R 3 = H) and thiocyanic acid 12 giving rise to the formation of 1-anilino-2,3-dihydro-1H-imidazole-2-thiones 7 (Scheme 1). 13,14 This reaction is considered to be initiated by a [3+2] cycloaddition step forming cycloadduct 5. Protonation at the exocyclic nitrogen atom of intermediate 5 followed by deprotonation of 6 (R 3 = H) at C-4 yields the final heteroaromatic product 7. Compounds 7 can be obtained also in the course of a one-pot reaction; the two reagents undergoing the cycloaddition reaction are generated in situ from α-halo carbonyl compounds 1 (X = Br, Cl), potassium thiocyanate, and phenylhydrazine. 15These findings prompted the investigation of this reaction with phenylazoalkenes 4 being fully substituted at the terminal carbon atom (R 2 , R 3 ≠ H;) and an excess of potassium thiocyanate in acetic acid (Scheme 1). Cycloadduct 5 (R 2 , R 3 ≠ H) is envisaged to be the first formed intermediate; however, lacking a hydrogen atom at 4-C, adduct 5 undergoes a further [3+2] cycloaddition reaction with thiocyanic acid at the azomethine imine function giving rise to the bicyclic product imidazo[1,5-b][1,2,4]triazole-2,5-dithione 8. 16 An alternative one-pot procedure also providing bicyclic products 8 involves the treatment of an α,α-disubstituted α-bromo carbonyl compound 1 (X = Br; R 2 , R 3 ≠ H) with excess of potassium thiocyanate in acetic acid and one equivalent of phenylhydrazine (Scheme 1). The presumed initial substitution of 1 with potassium thiocyanate is followed by conversion of the resultant α-thiocyanato carbonyl compound 2 into phenylhydrazone 3. The subsequent conjugate elimination reaction provides phenylazoalkene 4 and thiocyanic acid, both intermediates reacting further in the fashion outlined above and furnishing 8.Following this procedure 2-bromo-2-methylpropanal 1a gave (7aRS)-8a, 2-bromo-2-phenylpropanal 1b provided a 4:1 mixture of diastereomers 8b, which were separated by column chromatography (silica gel, ether) into colorless crystals of (7R*,7aS*)-8b and (7S*,7aS*)-8b; 17 similarly, 3-bromo-3-methylbutan-2-one 1c was converted into (7aRS)-8c. 18 The dithione structure of compounds 8 (as opposed to a conceivable thiazole structure) is support...

show abstract

Acyclic α‐Nitro Ketones: Synthesis and Reactivity

2021

Nitroalkanes

View full text Add to dashboard Cite

Conjugated azoalkenes. Part XVI. Reaction of some conjugated azoalkenes with β-nitrocarbonyl derivatives.

Cited by 14 publications

References 11 publications

Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation

Highly diastereoselective 1,3-dipolar cycloadditions of chiral non-racemic nitrones to 1,2-diaza-1,3-dienes: an experimental and computational investigation

Tandem [3 + 2] Cycloaddition Reaction of Azo-alkenes and Thiocyanic Acid: Extending the Scope of the Classical "Criss-Cross" Cycloaddition Reaction

Acyclic α‐Nitro Ketones: Synthesis and Reactivity

Contact Info

Product

Resources

About