Umsetzung von Acetylenderivaten mit disubstituierten Diazomethanverbindungen

Hüttel, Rudolf; Riedl, Josef; Martin, Hedwig; Franke, Karl

doi:10.1002/cber.19600930629

Cited by 64 publications

(13 citation statements)

References 13 publications

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“…Compound 3a then underwent partial conversion to 4a during recrystallization at ambient temperature. [8][9][10][11] Computed transition states for the various migration pathways are consistent with the observed ring contraction. In previous studies, similar [1s, 5s] sigmatropic shifts proceed to give products of ring expansion.…”

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confidence: 54%

Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

et al. 2019

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Formation of fused pyrazoles via intramolecular 1,3-dipolar cycloadditions of diazo intermediates with pendant alkynes are described. A subsequent thermal [1s, 5s] sigmatropic shift of these pyrazole systems resulted in a ring contraction to form spirocyclic pyrazoles. The limitations of this rearrangement were explored by changing the substituents on the non-migrating aromatic ring and by using substrates lacking an aromatic linkage to the propargyl group.

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confidence: 54%

Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

et al. 2019

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“…In the presence of a less reactive dienophile, compound 5 could undergo a phenyl migration analogous to a [ I , 51 sigmatropic phenyl shift (25)(26)(27)(28)(29) to give intermediate 6, which upon work-up gave compound 4b. Compound 6 most likely exists as the trimer 7 similar to the formation of trimethoxyboroxine (30).…”

Section: Introductionmentioning

confidence: 99%

Reactions of 2-phenyl-4H-1,3,2-benzodioxaborin, a stable ortho-quinone methide precursor

Chambers¹,

Crawford²,

Williams³

et al. 1992

Can. J. Chem.

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Thermolysis of 1-phenyl-4H-1,3,2-benzodioxaborins generated the corresponding ortho-quinone methides, which were found to undergo intermolecular cycloaddition reactions with ethyl vinyl ether, dihydropyran, p-methylstyrene, cyclohexene, and 1-ethoxy-1-z-trimethylsiloxy-1-propenes to give various substituted chromans. Intramolecular trapping of the quinone methides with an olefin led to the syntheses of several analogs of tetrahydrocannabinols. ortho-Quinone methides, generated by treatment of the 2-phenyl-4H-1,3,2-benzodioxaborins with a Lewis acid, react with various nucleophiles to give the corresponding 1,4-addition products. Thus, alkyl and aryl thiols, alcohols, amine, hydride, ally1 trimethylsilane, acetophenone, and diethylmalonate as well as some aryl compounds react with the quinone methide to give various 2-substituted phenols. Intramolecular reaction of the quinone methide with an aryl group led to the preparation of some 4-phenylchromans and tetralins. La thermolyse des 2-phknyl-4H-1,3,2-benzodioxaborines conduit aux ortho-quinomkthanes correspondantes qui subissent des rkactions de cycloaddition interrnolkculaires avec l'ethoxykthkne, le dihydropyrane, le p-mkthylstyrkne, le cyclohexkne et les 1 -6thoxy-1 -z-trimkthylsiloxyprop-1 -knes pour conduire a divers chromanes substituks. Le pikgeage intrarnolkculaire des quinomkthanes avec une olefine permet la synthkse de plusieurs analogues des tktrahydrocannabinols. Les ortho-quinomkthanes, prCparCs par traitement des 2-phknyl-4H-1,3,2-benzodioxaborines avec un acide de Lewis, rkagissent avec divers nuclkophiles pour donner les produits d'additions-1,4 correspondants. Ainsi, les alkyl-et aryl-thiols, les alcools, les amines, les hydrures, l'allyltrim~thylsilane, I'acCtophknone et le malonate d'kthyle ainsi que certains composks aromatiques rkagissent avec le quinomkthane pour conduire a divers phknols substituks en position 2. La reaction intramolCculaire des quinomkthanes avec un groupe aryle conduit a la prkparation de quelques 4-phknylchromanes et de tktralines.[Traduit par la rkdaction]

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“…The Auwers adducts, as well as 4H-pyrazoles resulting from their thermal rearrangement, were converted in 5-7 days at 20°C into 3,4,4-triphenyl-1H-pyrazol-5(4H)-one by the action of a catalytic amount of sulfuric acid in acetic acid. Under analogous conditions, the regioisomeric anti-Auwers adducts gave rise to 3,4,5-triphenyl-1H-pyrazole with an impurity of 4-(R-sulfonyl)-1,3,5-triphenyl-1Hpyrazoles.* In the reaction of diphenyldiazomethane with propynal only Auwers 3H-pyrazole was obtained [7], whereas in the reaction with 3-phenylpropynenitrile, only the anti-Auwers adduct was formed [13]. …”

mentioning

confidence: 99%

“…* In the reaction of diphenyldiazomethane with propynal only Auwers 3H-pyrazole was obtained [7], whereas in the reaction with 3-phenylpropynenitrile, only the anti-Auwers adduct was formed [13].…”

mentioning

confidence: 99%

“…Among such 1,3-dipoles, diphenyldiazomethane has been studied most thoroughly. Reactions of diphenyldiazomethane with unsymmetrically substituted acetylenes, such as propynal and phenylpropynal, propynenitrile, methyl but-2ynoate, and methyl 3-phenylprop-2-ynoate, were reported [7][8][9][10][11][12][13] to afford mainly two regioisomeric 3H-pyrazoles which were formed according and con-trary to the von Auwers rule. * Thermal and acidcatalyzed transformations of these cycloadducts were studied, and it was found that van Alphen-Hüttel rearrangement occurred in each case [14,15], which led to the formation of 1H-and/or 4H-pyrazole derivatives via 1,5-sigmatropic shift of the phenyl substituent.…”

mentioning

confidence: 99%

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Synthesis of 3H-pyrazoles by reaction of methyl and p-tolyl phenylethynyl sulfones with diphenyldiazomethane and their thermal and acid-catalyzed transformations

et al. 2015

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Methyl and p-tolyl phenylethynyl sulfones reacted with diphenyldiazomethane in diethyl ether at 20°C to give 1,3-dipolar cycloaddition products both according and contrary to the von Auwers rule, sulfonylsubstituted 3H-pyrazoles at a ratio of 1 : 1.5 and 1.3 : 1, respectively. On heating in toluene for 2 h, the Auwers adducts underwent van Alphen-Hüttel rearrangement with 1,5-sigmatropic shift of one phenyl substituent to afford sulfonyl-substituted 4H-pyrazoles. Under analogous conditions, the anti-Auwers adducts rearranged into sulfonyl-substituted N-phenyl-1H-pyrazoles containing a small amount of the denitrogenation product, sulfonyl-substituted cyclopropene. The Auwers adducts, as well as 4H-pyrazoles resulting from their thermal rearrangement, were converted in 5-7 days at 20°C into 3,4,4-triphenyl-1H-pyrazol-5(4H)-one by the action of a catalytic amount of sulfuric acid in acetic acid. Under analogous conditions, the regioisomeric anti-Auwers adducts gave rise to 3,4,5-triphenyl-1H-pyrazole with an impurity of 4-(R-sulfonyl)-1,3,5-triphenyl-1Hpyrazoles.* In the reaction of diphenyldiazomethane with propynal only Auwers 3H-pyrazole was obtained [7], whereas in the reaction with 3-phenylpropynenitrile, only the anti-Auwers adduct was formed [13].

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Umsetzung von Acetylenderivaten mit disubstituierten Diazomethanverbindungen

Cited by 64 publications

References 13 publications

Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

Reactions of 2-phenyl-4H-1,3,2-benzodioxaborin, a stable ortho-quinone methide precursor

Synthesis of 3H-pyrazoles by reaction of methyl and p-tolyl phenylethynyl sulfones with diphenyldiazomethane and their thermal and acid-catalyzed transformations

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