Cyclic guanidines. XVI. Synthesis and biological activities of tetracyclic imidazo(2,1-b)quinazolinone derivatives.

Ishikawa, Fumiyoshi; Yamaguchi, Hitoshi; Saegusa, Junji; Inamura, K.; Mimura, Takanori; Nishi, T.; Sakuma, Kazuhiko; Ashida, Shinji

doi:10.1248/cpb.33.3336

Cited by 13 publications

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“…1 H NMR, 13 C NMR, and mass spectra confirmed the formation of 16 (16.6 g, 85% yield). In a deviation from the literature (41), this ring-closure was accomplished in the absence of urea.…”

Section: Methodsmentioning

confidence: 91%

“…There is a remote chance that the carbamic acid 9 might add water to form 12 and 12 then might recyclize to uracil 13 . The synthesis of uracil derivatives by addition of amides to carbamate esters does have precedent with aromatic substrates ( , ), and we wondered whether such ring closures might be possible for aliphatic 12 and whether they might perhaps even occur for these substrates under milder conditions as compared to the aromatic substrates. The geometry of 12 positions the amide-N well for approach to the carboxyl-C (Figure ).…”

Section: Introductionmentioning

confidence: 99%

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Nitrosative Cytosine Deamination. An Exploration of the Chemistry Emanating from Deamination with Pyrimidine Ring-Opening

Rayat

Qian

Glaser

2005

Chem. Res. Toxicol.

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A discussion of nitrosative deamination of cytosine 1 is presented that argues for the formation of 6 by diazotization of 1 to cytosinediazonium ion 2 and its electrostatic complex 3, dediazoniation to 4 <--> 5, and amide-bond cleavage to 6. The reaction channels available to 6 include hydrolytic deglycation to 3-isocyanatoacrylonitrile 7, water addition to carbamic acid 9 with the possibility for re-closure to uracil 13, water addition to carbamic acid 9, and decarboxylation to 3-aminoacrylonitrile 10. With a view to the instability of the carbamic acid 9, the carbamate models ethyl (Z)-2-cyanovinylcarbamate 14 and (Z)-2-cyano-1-tert-butylvinylcarbamate 20 were studied. Acid-catalyzed hydrolysis of 14 leads to 2-amino-carbonylphenylcarbamate 15, and its cyclization yields the benzo-fused uracil quinazoline-2,4-dione 16. In contrast to the aromatic system 14, acid-catalyzed cyclization cannot compete with oligomerization in the case of 20, and 5-tert-butyluracil 22 is accessible only with base-catalysis. It is shown that 23, the parent of 10, also easily polymerizes. The experimental results provide a rationale as to why 9, 10, and 12 would have escaped detection in in vitro studies: they would have oligomerized. In contrast to the in vitro experiments, the oligomerizations of 9, 10, or 12 clearly are not relevant in vivo because of low monomer concentrations. With the exclusion of recyclization and of oligomerization in vivo, attention thus needs to focus on (Z)-3-aminoacrylonitrile 10 as the most likely deamination product of cytosine aside from uracil.

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“…1 H NMR, 13 C NMR, and mass spectra confirmed the formation of 16 (16.6 g, 85% yield). In a deviation from the literature (41), this ring-closure was accomplished in the absence of urea.…”

Section: Methodsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Nitrosative Cytosine Deamination. An Exploration of the Chemistry Emanating from Deamination with Pyrimidine Ring-Opening

Rayat

Qian

Glaser

2005

Chem. Res. Toxicol.

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“…Ishikawa et al . synthesized imidazo[2, 1‐ b ]quinazolin‐2(3 H )‐ones by heating ethyl 2‐(2‐chloroquinazolin‐3(4 H )‐yl)propanoate in ammoniacal ethanol . Scott and co‐workers carried out the preparation of racemic 3‐hydroxy anagrelide with only 10% yield .…”

Section: Introductionmentioning

confidence: 99%

Enantiospecific Synthesis of Imidazoquinazolin-2-ones via Base-Catalyzed Tandem Cyclization

Kumar

Barve

et al. 2017

ChemistrySelect

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A facile protocol for the enantiospecific synthesis of novel (S)‐3‐substituted imidazo[2, l‐b]quinazoline‐2‐ones via tandem reaction of substituted (S)‐3‐amino‐4‐aminomethylbenzoates and cyanogen bromide under basic conditions is explored. This tandem process involves addition reaction of substituted (S)‐3‐amino‐4‐aminomethylbenzoates to CNBr to yield 2‐imino tetrahydroquinazoline carboxylate intermediates followed by in situ intramolecular aminolysis to afford the triheterocyclic imidazo[2, l‐b]quinazoline‐2‐ones in good yields and high enantiomeric purity.

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ChemInform Abstract: Cyclic Guanidines. Part 16. Synthesis and Biological Activities of Tetracyclic Imidazo[2,1‐b]quinazolinone Derivatives.

Ishikawa¹,

Yamaguchi²,

Saegusa³

et al. 1986

Chemischer Informationsdienst

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Cyclic guanidines. XVI. Synthesis and biological activities of tetracyclic imidazo(2,1-b)quinazolinone derivatives.

Cited by 13 publications

References 0 publications

Nitrosative Cytosine Deamination. An Exploration of the Chemistry Emanating from Deamination with Pyrimidine Ring-Opening

Nitrosative Cytosine Deamination. An Exploration of the Chemistry Emanating from Deamination with Pyrimidine Ring-Opening

Enantiospecific Synthesis of Imidazoquinazolin-2-ones via Base-Catalyzed Tandem Cyclization

ChemInform Abstract: Cyclic Guanidines. Part 16. Synthesis and Biological Activities of Tetracyclic Imidazo[2,1‐b]quinazolinone Derivatives.

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