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Synlett 2003(8): 1151-1152
DOI: 10.1055/s-2003-39883
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

The First Synthesis of Novel 7-Oxo-7H-pyrrolo[3,2-d]pyrimidine 5-Oxides from 1-(5-Nitro-6-pyrimidinyl)-2-arylacetylenes

Inga Susvilo, Algirdas Brukstus, Sigitas Tumkevicius*
Department of Organic Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-2006 Vilnius, Lithuania
Fax: +370(5)2330987; e-Mail: sigitas.tumkevicius@chf.vu.lt;
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Publication History

Received 13 February 2003
Publication Date:
11 June 2003 (online)

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Abstract

Palladium-catalysed reaction of 4-amino-6-chloro-5-nitropyrimidine with arylacetylenes affords the corresponding 1-(4-amino-5-nitro-6-pyrimidinyl)-2-arylacetylenes, which in dry pyridine undergo smooth cyclisation to give 4-amino-6-aryl-7-oxo-7H-pyrrolo[2,3-d]pyrimidine 5-oxides in excellent yields.

Key words

catalysis - cyclisation - palladium - pyrimidines - pyrrolopyrimidines

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Typical Procedure for the Preparation of 1-(4-amino-5-nitro-6-pyrimidinyl)-2-arylacetylenes 2a-c. A mixture of compound 1 (0.2 g, 1.15 mmol), PdCl2(PPh3)2 (0.016 g, 0.023 mmol), CuI (0.0022 g, 0.0115 mmol) and dry Et3N (10 mL) was stirred under Ar atmosphere for 1 min. Then the corresponding arylacetylene (1.38 mmol) was added, the mixture was flushed with Ar and heated under stirring at 40 °C for 3 h. After cooling to r.t. the precipitate was filtered off and recrystallised to give compounds 2a-c.
Compound 2a: Yield 75%, mp 158-160 °C (from 1-butanol). IR (nujol): νmax = 3358, 3286 (NH2), 2214 (C≡C), 1582 (NO2) cm-1. 1H NMR (CDCl3): δ = 1.42 (2 H, br s, NH2), 7.31-7.89 (5 H, m, Ar-H), 8.62 (1 H, s, C2H). 13C NMR (DMSO-d 6): δ = 84.6, 84.9, 97.6, 120.1, 128.9 (2 C), 130.6, 132.1 (2 C), 144.03, 155.9, 159.1. MS: m/z (%) = 240 (26) [M+]. Anal. Calcd for C12H8N4O2: C, 60.00; H, 3.36; N, 23.32. Found: C, 60.19; H, 3.32; N, 23.60.
Compound 2b: Yield 89%, mp 175-177 °C (from EtOH). IR (nujol): νmax = 3457, 3314 (NH2), 2210 (C≡C), 1574 (NO2) cm-1. 1H NMR (DMSO-d 6): δ = 2.38 (3 H, s, CH3), 7.32 (2 H, d, J = 8 Hz, Ar-H), 7.52 (2 H, d, J = 8 Hz, Ar-H), 8.33 (2 H, br s, NH2), 8.56 (1 H, s, C2H). MS: m/z (%) = 254(48) [M+]. Anal. Calcd for C13H10N4O2: C, 61.41; H, 3.96; N, 22.04. Found: C, 61.52; H, 4.0; N, 21.99.
Compound 2c: Yield 68%, mp 160-162 °C (from 2-PrOH). IR(nujol): νmax = 3430, 3380 (NH2), 2211 (C≡C), 1578 (NO2) cm-1. 1H NMR (CDCl3): δ = 1.64 (2 H, br s, NH2), 6.89-7.31 (2 H, m, Ar-H), 7.40-7.93 (2 H, m, Ar-H), 8.64 (1 H, s, C2H). Anal. Calcd for C12H7FN4O2: C, 55.82; H, 2.73; N, 21.70. Found: C, 55.89; H, 2.68; N, 21.86.

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Typical Procedure for the Preparation of 4-Amino-6-aryl-7-oxo-7 H -pyrrolo[3,2- d ]pyrimidine 5-oxides 3a-c. A solution of the corresponding 2a-c (1 mmol) in dry pyridine (5 mL) was refluxed for 15 min. After cooling to r.t. the precipitate was filtered off, the filtrate was concentrated under reduced pressure. The precipitate was combined with the earlier obtained and recrystallised to give compounds 3a-c as dark violet solids.
Compound 3a: Yield 95%, mp>250 °C (dec.) (from toluene). IR (nujol): νmax = 3328, 3237 (NH2), 1724 (CO)
cm-1. 1H NMR (DMSO-d 6): δ = 7.41-8.52 (5 H, m, Ar-H), 7.72 (1 H, br s, NH), 8.22 (1 H, br s, NH), 9.61 (1 H, s, C2H). 13C NMR (DMSO-d 6): δ = 122.0, 125.4, 126.9 (2 C), 128.4 (2 C), 130.0, 149.0, 151.4 (2 C), 160.5, 186.3. MS: m/z
(%) = 240 (96) [M+]. Anal. Calcd for C12H8N4O2: C, 60.00; H, 3.36; N, 23.32. Found: C, 60.26; H, 3.29; N, 23.35.
Compound 3b: Yield 90%, mp>250 °C (dec.) (from toluene). IR (nujol): νmax = 3363, 3231 (NH2), 1728 (CO)
cm-1. 1H NMR (DMSO-d 6): δ = 2.4 (3 H, s, CH3), 7.41 (2 H, d, J = 8 Hz, Ar-H), 7.43 (1 H, br s, NH), 8.31 (1 H, br s, NH), 8.38 (2 H, d, J = 8 Hz, Ar-H), 8.74 (1 H, s, C2H). MS: m/z (%) = 254 (33) [M+]. Anal. Calcd for C13H10N4O2: C, 61.41; H, 3.96; N, 22.04. Found: C, 61.45; H, 3.98; N, 22.09.
Compound 3c: Yield 87%, mp>250 °C (dec.) (from toluene). IR (nujol): νmax = 3330, 3245 (NH2), 1727 (CO)
cm-1. 1H NMR (DMSO-d 6): δ = 6.93 (1 H, br s, NH), 7.71 (1 H, br s, NH), 6.86-7.87 (4 H, m, Ar-H), 8.58 (1 H, s, C2H). Anal. Calcd for C12H7FN4O2: C, 55.82; H, 2.73; N, 21.70. Found: C, 55.79; H, 2.66; N, 21.65.