Pteridine, LXIV: Synthese und Eigenschaften von Thiolumazinen

Abstract

Einige 3-Methyl-2-thiolumazine (6-9) werden synthetisiert und durch pK-Werte sowie UVSpektren charakterisiert. Die Umsetzungen der 2-Thiolumazine 11 -13 mit 1,2-Dibromethan bzw. Pteridines, LXIV Synthesis and Properties of ThiolumazinesThe synthesis of various 3-methyl-2-thiolumazines (6-9) is described and their characterization based on pK values and UV spectra. The reaction of 2-thiolumazines (11 -13) with 1,2-dibromoethane or 1,3-dibromopropane leads preferentially to the formation of thiazolo-and thiazino [2,3-b]-pteridines (15-19), whereas the [3,2-a]isomers are minor reaction products as seen from the isolation of 7,8-dimethyl-5-oxo-5H-1,2-dihydrothiazolo[3,2-a]pteridine (20). The oxidative transformations of various thiolumazines by hydroperoxides are mentioned.

Fused pyrimidine systems: XVI. Electrophilic intramolecular cyclization of 2-(alkenylsulfanyl)pteridin-4(3H)-ones

“…The advances in synthetic chemistry of pteridine belong mainly to the field of its functional derivatives and they are recently summarized in a review [4]. The heterofused pteridine compounds are less studied, in particular, thiazolo [2,3-d]-and thiazino [2,3-d]pteridines, which are as a rule obtained by cyclocondensation of methyl 2-aminopyrazine-3-carboxylate with cyclic iminothioacetals [5] or of pteridine-2-thiones with vicinal dibromoalkenes [6,7]. The latter procedure is although sufficiently selective but it does not allow the preparation of compounds with functional groups in the fused ring.…”

“…С NMR spectrum (DMSO-d6 ), δ, ppm: 31.05 (С 8 ), 33.72 (СН 2 ), 60.44 (С 9 ), 126.38 (С Ar ), 128.59 (2С Ar ), 129.01 (2С Ar ), 129.73 (С 4а ), 134.10 (С Ar ), 143.08 (С 3 ), 146.30 (С 10а ), 147.25 (С 2 ), 165.47 (С 6а ), 169.83 (С 5 ). Found, %: C 54.81; H 3.73; N 17.01; S 19.39.…”

Synthesis of new heterocondensed pteridines

“…The aromatic and heteroaromatic 2-aminoester or 2-aminonitrile compounds undergo readily cyclization which allow convenient preparation of variety of condensed pyrimidines [6]. We have recently reported the synthesis of novel heterocyclic fused pyrimidine systems [7-10] in one-pot annelation by the reaction of 2-aminoester or 2-aminonitrile compounds with the N-[bis-(methylthio)methylene]amino (BMMA) or analogs of BMMA reagents.Although several methods are available for the syntheses of pteridines [11][12][13][14][15], the methodology whereby the pyrazine intermediate requiring the addition of N-3 to complete the pteridine ring has not been widely used [12].Previously we have been interested in the synthesis of substituted heterocycles containing a thienopyrimidine system [7][8][9][10]16,17]. The present paper follows that line of research by reporting on a new series of linear fusion of 2-aminopyrazine 1, in which imidazole, pyrimidine, thiazole, thiazine and pyrazine moieties were annelated, yielding novel tricyclic ring systems.…”

“…Although several methods are available for the syntheses of pteridines [11][12][13][14][15], the methodology whereby the pyrazine intermediate requiring the addition of N-3 to complete the pteridine ring has not been widely used [12].…”

“…The thiazolo[2,3-b]pteridine (8) and thiazino[2,3-b]pteridine (9) systems have already been synthesized earlier in different research groups [14,15] utilizing multi-step approaches different from the method reported in this paper. 2-Aminopyrazine 1 with 2-(methylthio)-1,4,5,6-tetrahydropyrimidine at 150°furnished identical product 11 in a neat reaction or in hexamethylphosphoric triamide (HMPTA).…”