Synthesis and Isomerization of Adducts of Azodicarbonyl Compounds and Cyclopentadiene

1972 ◽  
Vol 50 (3) ◽  
pp. 371-380 ◽  
Author(s):  
J. A. Campbell ◽  
Donald Mackay ◽  
T. D. Sauer
Keyword(s):  
Thermal Isomerization ◽  
Diels Alder ◽  
Derivatives Of

The synthesis of a range of bicyclic Diels–Alder adducts (structures b) of cyclopentadiene with symmetrical and unsymmetrical azodicarbonyl compounds is described. Thermal isomerization of these adducts to the bicyclic 1,3,4-oxadiazines (structures c and d) is especially rapid with bulky acyl groups. In unsymmetrical adducts with acyl groups of markedly different size, the larger group dictates completely the direction of isomerization. Adducts with two different aroyl groups give both isomers.Spectroscopic properties of the adducts, the oxadiazines and the dihydro derivatives of the oxadiazines are described.

Substituent Effects in the Thermal Isomerization of 1,2-Dicarbonyl Derivatives of 3,6-Bridged 1,2,3,6-Tetrahydropyridazines

1975 ◽  
Vol 53 (4) ◽  
pp. 535-541 ◽  
Author(s):  
John A. Campbell ◽  
Ian Harris ◽  
Donald Mackay ◽  
Timothy D. Sauer
Keyword(s):  
Substituent Effects ◽  
Thermal Isomerization ◽  
Diels Alder ◽  
Effect Of Substituents ◽  
Rotation Rates ◽  
Derivatives Of ◽  
Cyclic Intermediate

The Diels–Alder adducts of cyclopentadiene and azodiacyls or azodiaroyls isomerize to 1,3,4-oxadiazines at rates which show a trend qualitatively related to the rotation rates of the corresponding N,N-dimethylamides. The isomerizations probably occur by a cyclic concerted mechanism.The ring substituents in the adducts of 1,4-dimethyl-2,3-diphenylcyclopentadiene and azodibenzoyl or azodiacetyl accelerate the isomerization; the kinetic evidence supports a cyclic intermediate in the reaction in isooctane as solvent but is more consistent with a dipolar intermediate in aqueous ethanol.Some generalizations about the effect of substituents on the isomerization are presented on the basis of these and earlier experiments.

Thermal isomerization of N-oxalyl derivatives of diamino acids

1993 ◽  
Vol 33 (5) ◽  
pp. 1121-1123 ◽  
Author(s):  
Berhanu M. Abegaz ◽  
Peter B. Nunn ◽  
André De Bruyn ◽  
Fernand Lambein
Keyword(s):  
Thermal Isomerization ◽  
Derivatives Of

Cycloadditionen, XXII [1]. Synthese und thermische Reaktion von S-(Alkyl/Aryl)- 2.3-butadienthiosäure-estern / Cycloadditions, XXII [1]. Synthesis and Thermal Reaction of S-(Alkyl/Aryl)-2,3-butadienethioates

1994 ◽  
Vol 49 (4) ◽  
pp. 542-550 ◽  
Author(s):  
Gerhard Himbert ◽  
Dieter Fink
Keyword(s):  
Alder Reaction ◽  
Thermal Reaction ◽  
Diels Alder ◽  
Alkyl Aryl ◽  
Diels Alder Reaction ◽  
Ester Moiety ◽  
Derivatives Of

While the S-alkyl- or S-phenyl-2,3-butadienethioates 4 a-c are synthesized via the usual “Wittig ylide way”, the corresponding 2-methyl-2,3-butadienethioates 9 a-d and the 2-methyl-4.4-diphenyl-2,3-butadienethioates 9 e,f are obtained by condensation of the allenic acids 7 a,b with the thiols and thiophenols 8 in the presence of dicyclohexylcarbodiimide (DCC) and a catalytic am ount of 4-dimethylaminopyridine (DMAP). In contrast to N- or O-phenyl 2,3- butadienamides or -esters, resp., the phenyl derivatives of 4 and 9 do not undergo the intram olecular Diels-Alder reaction, but by heating, all representatives of 4 only decompose, while 9 a-d and 9 e,f rearrange to 3-alkyl(aryl)thio-2-cyclobuten-1-ones 12a-d and to 3-arylthio- 1-naphthols 14a, b, resp. Heating of the cyclobutenone 12d in the presence of N-methylaniline furnishes the 2-butenanilide 16. On reacting 1-phenylthio-1-propyne 17 with diphenylketene 18, the diphenylacetate 19 is isolated, where the naphthol derivative 14a represents the ester moiety.

Inverse electron demand Diels–Alder reactions with aminomethyl derivatives of 3-arylhydroxycoumarins

2016 ◽  
Vol 52 (7) ◽  
pp. 460-466 ◽  
Author(s):  
Galyna P. Mrug ◽  
Kostyantyn M. Kondratyuk ◽  
Svitlana P. Bondarenko ◽  
Mykhaylo S. Frasinyuk
Keyword(s):  
Diels Alder ◽  
Inverse Electron Demand ◽  
Aminomethyl Derivatives ◽  
Derivatives Of ◽  
Electron Demand

An examination of VANOL, VAPOL, and VAPOL derivatives as ligands for asymmetric catalytic Diels–Alder reactions

2006 ◽  
Vol 84 (10) ◽  
pp. 1487-1503 ◽  
Author(s):  
Douglas P Heller ◽  
Daniel R Goldberg ◽  
Hongqiao Wu ◽  
William D Wulff
Keyword(s):  
Asymmetric Catalysis ◽  
Methyl Acrylate ◽  
Lewis Acids ◽  
Alder Reaction ◽  
Diels Alder ◽  
Asymmetric Catalytic ◽  
Diels Alder Reaction ◽  
Positive Cooperativity ◽  
Derivatives Of ◽  
Methyl Phenyl

Several derivatives of the vaulted biaryl ligand VAPOL were prepared and evaluated as chiral ligands for aluminum Lewis acids in the catalytic asymmetric Diels–Alder reactions of methyl acrylate and methacrolein with cyclopentadiene. The substituents on VAPOL were introduced into the 6- and 6′-positions in an effort to further extend the chiral pocket of the major groove, which contains the phenol functions at the 4- and 4′-positions. The set of four new ligands that have been prepared have the following groups introduced into the 6- and 6′-positions of VAPOL: bromide, methyl, phenyl and 3,5-di-t-butylphenyl. All of these ligands give lower asymmetric inductions than the unsubstituted VAPOL for the Diels–Alder reactions of both methyl acrylate and methacrolein. The positive cooperativity of added carbonyl compounds on the autoinduction in the Diels–Alder reaction of methyl acrylate and cyclopentadiene were also investigated with the VANOL and VAPOL ligands as well as the 6,6′-dibromo and 6,6′-diphenyl derivatives of VAPOL. Only the reaction with VAPOL showed any significant positive cooperativity. The reaction with VANOL was sluggish at –78 °C, but at higher temperatures, the reaction did exhibit positive cooperativity that was similar to that of VAPOL. Finally, no positive cooperativity was observed with the VAPOL ligand for the reaction of methacrolein and cyclopentadiene.Key words: Diels–Alder, asymmetric catalysis, vaulted biaryl ligands, VANOL, VAPOL.

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