Synthesis of condensed heteroaromatics: novel synthesis of aminoquinolizinone derivatives as anti-HIV agents

Section: Resultsmentioning

confidence: 99%

Reaction of β‐dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3‐ and 5‐substituted isoxazoles

Rosa

Machado

Bonacorso

et al. 2008

“…Quinolizine derivatives have attracted a great deal of interest, due to their biological activities, such as anti-HIV, a n t i -t u m o r, anti-hypertensive, anti-allergic, anti-ulcer, anti-mycobacterial, anti-bacterial, anti-inflammatory and as potent selective human steroid [139]. Human steroid 5α-reductase (5αR) is a family of two isoenzymes (types 1 and 2) that convert testosterone to the more potent androgen dihydrotestosterone (DHT).…”

Section: Cyclization Of Enaminonesmentioning

confidence: 99%

“…Human steroid 5α-reductase (5αR) is a family of two isoenzymes (types 1 and 2) that convert testosterone to the more potent androgen dihydrotestosterone (DHT). Selective inhibition of (5αR) is currently investigated as a potential therapeutic tool for the treatment DHT-related skin disorders, such as acne, alopecia, male baldness and hirsutism [139]. Reactions of enaminones 248 with malononitrile in refluxing ethanol and in the presence of catalytic amounts of piperidine afforded aminoquinolizinone derivatives.…”

Section: Cyclization Of Enaminonesmentioning

confidence: 99%

“…formation of aminoquinolizinone derivatives 2 5 1 i s assumed to proceed via initial attack of the anion of the first malononitrile molecule on the cyclic carbonyl carbon of compound 248 to form the ylidene malonitrile derivative 249 that then cyclizes into 250 with addition of a second malonitrile molecule to the enaminone double bond of 2 5 0, which loses a molecule of dimethylamine and cyclizes to afford the quinolizinone derivative 251 ( Figure 88) [139].…”

Section: Jul-aug 2004 483mentioning

confidence: 99%

See 1 more Smart Citation

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Negri

Kascheres

2004

176

Enaminoketones and esters are gaining increased interest, particularly cyclic-β-enaminoesters, which are known as important intermediates for the synthesis of heterocycles and natural products, because the enantioselective preparation of highly functionalized compounds is of central importance in synthetic chemistry. Enaminones are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. Enaminoketones and enaminonitriles have proven to be versatile building blocks for the synthesis of various heterocycles such as pyridine, pyrimidine and pyrrole derivatives. Enaminones systems have "enone" character, and may act as acceptors in both 1,2 and 1,4-additions. In this way the enaminone serves as a scaffold for annulation, and can gain access to systems such as pyrroles indolizidines, quinolizidines and perhydroindoles, all of which are common motifs in alkaloid structures. Enaminones are frequently employed as building blocks for the preparation of a variety of bicyclic compounds of biological interest and have been recently recognized as potential anticonvulsant compounds. Since a large number of developments in the use of enaminones in heterocyclic synthesis have occurred, a review of the recent developments in the synthetic approaches, covering the literature since 1995 until 2004, to these interesting molecules and their useful chemical transformations and biological activity can be considered of considerable value.J. Heterocyclic Chem., 41, 461 (2004).Enaminoketones. Introduction.The term enaminone was introduced by Greenhill to define the enamine of a 1,3-diketone, β-ketoester or similar 1,3-difunctional reagents, and is used to indicate any compound containing the conjugated system N-C=C-C=O [1]. Enaminones are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. The chemistry of the enaminocarbonyl group 1 is potentially an area of considerable scope when one considers that there are present in this moiety, three nucleophilic sites (a, c and e) and two electrophilic sites (b and d) [2][3][4] (Figure 1).Theorically, primary and secondary acyclic enaminones can exist in three tautomeric forms: ketamino form, iminoenol form and oxoimino form [1][2][3]. There is also evidence that cyclic enaminones exist primarily in the enaminoketo form. A study of cyclic enaminoketones shows that these compounds have a significant steric fator in the six-membered ring. The six-membered ring enaminoketones are only slightly stronger bases than the saturated amines, whereas five-and-seven membered rings are much stronger bases than saturated amines. This has been attributed to a large steric strain present in six-membered enaminoketones [5].β-Aminoenones or enaminoketones can exist in four conformations owing to restricted rotations around the C=C double and C-C=O single bonds [3]. Enaminones with primary or secondary amino groups can exist in both Z-and E-forms. If there is a...

“…Reactions of the 2-oxo-4-(2-dimethylaminoethenyl)-2H-chromene-3-carbonitrile (4) and 2-amino-4-(2-dimethylaminoethenyl)quinoline-3-carbonitrile (5) with benzotriazol-1-yl-acetic acid hydrazide (6) affords the substituted [1,2,4]triazolo [1,5-a]pyrido [3,4-c]coumarines 9 and quinoline 12, respectively. Treatment of 4 with 2-amino-pyridine, glycine, urea, 3-aminocrotononitrile or cyanothioacetamide affords 14-18, respectively.…”

mentioning

confidence: 99%

Synthesis and biological effects of new derivatives of azines incorporating coumarin

Al‐Omran

El‐Khair

2003

Self Cite

New synthetic routes for triazolopyridine, pyridopyrimidine, pyridotriazine, imidazopyridine and pyridazine derivatives incorporating a coumarin moiety with interesting biological activities are reported. Reactions of the 2-oxo-4-(2-dimethylaminoethenyl)-2H-chromene-3-carbonitrile (4) and 2-amino-4-(2-dimethylaminoethenyl)quinoline-3-carbonitrile (5) with benzotriazol-1-yl-acetic acid hydrazide (6) affords the substituted [1,2,4]triazolo [1,5-a]pyrido [3,4-c]coumarines 9 and quinoline 12, respectively. Treatment of 4 with 2-amino-pyridine, glycine, urea, 3-aminocrotononitrile or cyanothioacetamide affords 14-18, respectively. Treatment of 3-amino-3,4-dihydro-4-imino-chromeno[3,4-c]pyridin-5-one (10) with α-chloroacetylacetone affords pyridotriazine derivative 21. Compound 4 was also coupled with benzenediazonium chloride to afford 2-oxo-4-[2-oxo-1-(phenyl-hydrazono)-ethyl]-2H-chromene-3-carbonitrile 25. Treatment of the latter product with malononitrile afforded the 1-phenyl-3-(3'-Cyano-2'-oxo-coumarin-4'-yl)-6-oxopyridazine-5-carbonitrile (27). The structures of the newly synthesized compounds have been established on the basis of analytical and spectral data. The recent literature is enriched with progressive finding about the synthesis and pharmacological results of fused heterocycles. In conjunction with previous interest in the syntheses of polyfunctionally substituted heterocycles with potential biological activites [1][2][3][4][5]. It was interesting to study the behaviour of system A towards a variety of chemical reagents, as a new synthetic route to heterocyclic nitrogen containing compounds, such as triazolopyridine, pyridopyrimidine, pyridotriazine, imidazopyridine, pyridine and pyridazine derivatives incorporating a coumarin moiety. The importance of the above compounds is due to their diverse pharmaceutical activities [6][7][8][9][10][11][12][13] and as thermal-transfer printing dye [14].