Synthesis of new N-Benzoxazole and N-Benzothiazole derivatives of 3-(4-Substituted- phenyl)aminoisoxazol-5(2H)-ones and comparison of their base induced rearrangement

Khalafy, Jabbar; Marjani, Ahmad Poursattar; Ebrahimlo, Ali Reza Molla

doi:10.1590/s0103-50532006000300021

Cited by 9 publications

(3 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Again loss of carbon dioxide, as found earlier by Woodman [14], occurred with a rearrangement possibly involving cyclic intermediates to provide the amide group of 13 [15]. The energetics of possible mechanistic pathways for this process were explored using a density functional approach (ωB97XD functional, 6-311G(d,p) basis set and SCRF(CPCM) continuum solvation method for ethanol as a model polar solvent).…”

Section: Resultsmentioning

confidence: 93%

N-heteroatom substitution effect in 3-aza-cope rearrangements

Gomes

Pinto

Glória

et al. 2013

Chemistry Central Journal

View full text Add to dashboard Cite

BackgroundThe nature of the heteroatom substitution in the nitrogen of a 3-aza-Cope system is explored.ResultsWhile N-propargyl isoxazolin-5-ones suffer 3-aza-Cope rearrangements at 60°C, the corresponding N-propargyl pyrazol-5-ones need a higher temperature of 180°C for the equivalent reaction. When the propargyl group is substituted by an allyl group, the temperature of the rearrangement for both type of compounds is less affected by the nature of the heteroatom present. Treatment with a base, such as ethoxide, facilitates the rearrangement, and in the case of isoxazol-5- ones other ring opening reactions take precedence, involving N–O ring cleavage of the 5-membered ring. However when base-catalysed decomposition is prevented by substituents, products arising from a room temperature aza-Cope rearrangement are isolated. A possible mechanistic pathway based on free energies derived from density functional calculations involving cyclic intermediates is proposed.ConclusionsThe nature of the heteroatom substitution in the nitrogen of a 3-aza-Cope system leads to a remarkable difference in the energy of activation of the reaction.

show abstract

Section: Resultsmentioning

confidence: 93%

N-heteroatom substitution effect in 3-aza-cope rearrangements

Gomes

Pinto

Glória

et al. 2013

Chemistry Central Journal

View full text Add to dashboard Cite

show abstract

“…We have recently extended this work by noting 3,4 that the reaction of 3-(4-substitutedphenyl)aminoisoxazol-5(2H)-ones (3) and (4) with triethylamine leads to the formation of indoles (5), or imidazobenzothiazoles (6) respectively, and carbon dioxide, an outcome that is formally the same as that achieved by photolysis or pyrolsis 5 …”

Section: Introductionmentioning

confidence: 88%

The synthesis of potential DNA intercalaters 1. Heterocycles from the reaction of aryl bis-isothiocyanates

Ebrahimlo¹,

Khalafy²

2008

Arkivoc

Self Cite

View full text Add to dashboard Cite

show abstract

“…The reaction of thiocarbamoylcyanoacetates 2a-e with hydroxylamine by a modification of Worall [22] procedures in aqueous ethanol under reflux conditions afforded the corresponding 5-aminoisoxazoles 3a-e. The mechanism of the reaction is shown in the following Scheme: CO We have reported [19][20][21] that the reaction of diethyl arylthiocarbamoylmalonate with hydroxylamine under reflux conditions gave 3-arylamino-isoxazol-5(2H)-ones, but the reaction of ethyl 3-arylamino-2-cyano-3-thioxopropanoates 2a-e with hydroxylamine under reflux conditions gave the corresponding 5-aminoisoxazoles 3a-e in good yields. The formation of isoxazoles instead of isoxazolones may be due to the higher electronegativity of cyano group, which in this case reacts with nucleophilic oximino group to form the corresponding aminoisoxazoles.…”

mentioning

confidence: 99%

The synthesis of new 5-aminoisoxazoles by reaction of thiocarbamoylcyanoacetates with hydroxylamine

Khalafy

Dilmaghani

Soltani

et al. 2008

Chem Heterocycl Comp

View full text Add to dashboard Cite

The reaction of thiocarbamoylcyanoacetates with hydroxylamine in ethanol under reflux conditions has provided a convenient method for the synthesis of 5-aminoisoxazoles.Isoxazoles play an important role in biochemistry, organic chemistry, and bioorganic chemistry. The biological activity of substituted isoxazoles [1] has made them a focus of medicinal chemistry over the years. Isoxazoles are potent, selective agonists of human cloned dopamine D4 receptors [2] and exhibit GABA A antagonistic [3], analgesic [3], anti-inflammatory [4], ulcerogenic [4], antifungal [5], antimicrobial [5], COX-2 inhibitory [6, 7], antinociceptive [8], and anticancer [9] activities. Many synthetic methods have been employed in the synthesis of isoxazoles [10], including the reactions of hydroxylamine with 1,3-dicarbonyl compounds [11], α,β-unsaturated carbonyl compounds [12], and α,β-unsaturated nitriles [13]. The reaction of oxime-derived dianion and ester [14] or amide [15, 16] also provides isoxazoles. [3+2] Cycloaddition reactions between alkynes and nitrile oxides have been also developed [17, 18]. However, these methods often require strong bases, strong mineral acids, and high temperatures, or provide poor regioselectivity. We have reported that the reaction of o-, m-, and p-substituted diethyl phenylthiocarbamoylmalonates with hydroxylamine under reflux conditions gave o-, m-, and p-substituted 3-phenylaminoisoxazol-5(2H)-ones [19-21]. CH NH S X CO 2 Et CO 2 Et O N H N H EtO 2 C O X C NH 2 OH EtOH X = H, 2-Me, 2-MeO, 3-Br, 4-Br, 3-Me, 4-Me, 4-CO 2 Et, 4-NO 2 __________________________________________________________________________________________

show abstract

Synthesis of new N-Benzoxazole and N-Benzothiazole derivatives of 3-(4-Substituted- phenyl)aminoisoxazol-5(2H)-ones and comparison of their base induced rearrangement

Cited by 9 publications

References 13 publications

N-heteroatom substitution effect in 3-aza-cope rearrangements

N-heteroatom substitution effect in 3-aza-cope rearrangements

The synthesis of potential DNA intercalaters 1. Heterocycles from the reaction of aryl bis-isothiocyanates

The synthesis of new 5-aminoisoxazoles by reaction of thiocarbamoylcyanoacetates with hydroxylamine

Contact Info

Product

Resources

About