TY - JOUR
T1 - Tautomerism and ionisation of purin-8-one and its N-methyl derivatives
AU - Lichtenberg, Dov
AU - Bergmann, Felix
AU - Rabat, Miriam
AU - Neiman, Zohar
N1 - Funding Information:
(atpH 10); RF (A) 0.38; RF (B) 0-65 (violet fluorescence)(Found: C, 39-2; H, 3.3; N, 30.2; S , 17.3. C,H6N40Srequires C, 39.6; H, 3.3; N, 30-8; S, 17.6%).l-MethyZpurin-&one (4) .-A solution of l-methyl-6-mercaptopurin-&one (10 g) in 1% ammonia (100 ml) wasrefluxed with Raney nickel (4 g) for 1-5 h, filtered, andevaporated in vacuo. The residue was extracted withboiling dimethylformamide (100 ml) . Upon cooling, com-pound (4) crystallised in fine needles (as%), decomp.>300"; Am= (pH 1) 287 nm (E 15,000); RF (A) 0-33;RF (B) 0.54 (Found: C, 47.6; H, 4.3; N, 37.1. C,H6N40requires C, 48.0; H, 4.0; N, 37.3%).CNDOI2 CuZcuZutions.-The CND0/2 Fortran programof the QCPE (No. 100) was slightly modified by Dr. A. Y .Meyer (Department of Organic Chemistry, Hebrew Uni-versity). Since no data on the exact geometry of purin-8-one are reported, the skeleton was constructed by com-bination of the pyrimidine system of purine l5 and theimidazolone portion of uric acid.ls The new NH bond inthe protonated forms was assigned a length of 0.9 A ;preservation of all angles was assumed. The results(Table 4) are thus of a tentative character.This work was supported in part by the Centre Nationalde la Recherche Scientifique, under the responsibility ofProfessor B. Pullman, Institut de Biologie Physico-Chimique, Paris.[2/985 Received, 2nd May, 19721D. G. Watson, R. M. Sweet, and R. E. Marsh, Acta Cvyst.,1965, 19, 573.16 H. Ringertz, A d a Cryst., 1966, 20, 397
PY - 1972
Y1 - 1972
N2 - U.v. and n.m.r. spectra show that in aqueous solutions purin-8-one is present predominantly as the 7H,9H-tautomer. Anion formation takes place preferentially at N-9. Protonation of purin-8-one and its 7- and 9-methyl derivatives occurs at N-1 and causes splitting of the 6-H and 2-H n.m.r. signals. In purin-8-one and its N-methyl derivatives, the 2-H is more deshielded than the 6-H; the reverse is the case for purine itself.
AB - U.v. and n.m.r. spectra show that in aqueous solutions purin-8-one is present predominantly as the 7H,9H-tautomer. Anion formation takes place preferentially at N-9. Protonation of purin-8-one and its 7- and 9-methyl derivatives occurs at N-1 and causes splitting of the 6-H and 2-H n.m.r. signals. In purin-8-one and its N-methyl derivatives, the 2-H is more deshielded than the 6-H; the reverse is the case for purine itself.
UR - http://www.scopus.com/inward/record.url?scp=37049139481&partnerID=8YFLogxK
U2 - 10.1039/P19720002950
DO - 10.1039/P19720002950
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:37049139481
SN - 1472-7781
SP - 2950
EP - 2953
JO - Journal of the Chemical Society, Perkin Transactions 1
JF - Journal of the Chemical Society, Perkin Transactions 1
ER -