ChemInform Abstract: Synthesis of Various Thienyl‐ and Selenienylpyrimidines.

Gronowitz, Salo; Hoernfeldt, A.‐B.; Kristjansson, V.; Musil, Tomáš

doi:10.1002/chin.198643186

Cited by 15 publications

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“…2,4-Dibromopyrimidine (2.7 g, 48 %) was obtained as a white solid mp 66-68 °C. Spectral characteristics identical to literature [12]. In this publication [12], 2,4-dibromopyrimidine was obtained with a 10 % yield by distillation.…”

Section: 4-dibromopyrimidine (2)mentioning

confidence: 91%

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Metalation of bromodiazines. Diazines XL

Decrane¹,

Plé²,

Turck³

2005

Journal of Heterocyclic Chemistry

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The syntheses of 2-bromopyrazine, 2,4-dibromopyrimidines, and 3-bromo-6-phenylpyrazine were improved and their metalation with lithium alkylamides was studied.J. Heterocyclic Chem., 42, 509 (2005).The ortho directed metalation of various halogenated diazines has been extensively studied [1], however only one example of metalation of a bromo diazine: the 5-bromopyrimidine, has been reported in the literature by Kress [2] (Scheme 1).In the pyridine series, the metalation reaction of -2, -3 and -4-bromopyridines has been investigated [3,4] and was generally successful with 1 equivalent of lithium diisopropylamide at -78 °C in tetrahydrofuran.Our purpose was to study the metalation reaction of bromo derivatives of diazines. An example for each diazine series was chosen: 2-bromopyrazine, 2,6-dibromopyrimidine and 3-bromo-6-phenylpyridazine. This choice was mainly governed by the accessibility to these bromo derivatives.Synthesis of 2-Bromopyrazine 1.After completion of this work, a synthesis of 1 was published by Schlosser [5] using chloropyrazine and bromotrimethylsilane, with a 49 % yield. We tested several methods: direct metalation of pyrazine [6], Craig's method [7] starting from aminopyrazine, bromine-chlorine exchange with potassium bromide [8], or phosphorous tribromide [9].All these methods had some drawbacks (poor yields or difficulty to purify) and all the things considered, we chose the old method of Spoerri [10] (Scheme 2) starting from pyrazinone which was synthesized by the method of Konokahara [11] using glycinamide chlorhydrate and glyoxal with a 70 % yield.The synthesis of Spoerri used a mixture of phosphorous oxybromide and pentabromide as brominating agent and gave a mixture of monobromo and dibromopyrazine. We did not use pentabromide to avoid the formation of the dibromo derivative. With 2 equivalents of phosphorous oxybromide, no dibromopyrazine was formed and we obtained a 46 % yield of 1 after distillation.Synthesis of 2,4-Dibromopyrimidine 2.The same route as above was used starting from uracil. This reaction was described by Gronowitz [12] with a 10 % yield. We were able to improve this yield to 48 % by changing the purification process (column chromatography instead of distillation (Scheme 3).Synthesis of 3-Bromo-6-phenylpyridazine 7.Starting from 2,6-dichloropyridazine 3, the following route was developed (Scheme 4).

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Section: 4-dibromopyrimidine (2)mentioning

confidence: 91%

“…This reaction was described by Gronowitz [12] with a 10 % yield. We were able to improve this yield to 48 % by changing the purification process (column chromatography instead of distillation (Scheme 3).…”

Section: Synthesis Of 24-dibromopyrimidinementioning

confidence: 99%

Metalation of bromodiazines. Diazines XL

Decrane¹,

Plé²,

Turck³

2005

Journal of Heterocyclic Chemistry

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“…Reversing the pattern of halide and boronate also provides the 2‐arylselenophene derivatives. For example, 5‐bromopyrimidines and selenophen‐2‐ylboronic acid in the presence of Pd(PPh 3 ) 4 catalyst led to the 2‐heteroarylated selenophenes in 48–58 % yields (Scheme , top) . The reaction of selenophen‐2‐ylboronic acid and a 4‐chloropyrrolo[2,3‐d]pyrimidine derivative in the presence of 5 mol % Pd(OAc) 2 and 12 mol % TPPTS as catalytic system (TPPTS: 3,3′,3′′‐phosphanetriyltris(benzenesulfonic acid) trisodium salt) also gave the corresponding 2‐heteroarylselenophene in 64 % yield (Scheme , bottom)…”

Section: C2‐arylation Of Selenophenesmentioning

confidence: 99%

Access to (Hetero)arylated Selenophenes via Palladium‐catalysed Stille, Negishi or Suzuki Couplings or C−H Bond Functionalization Reaction

et al. 2017

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(Hetero)aryl‐substituted selenophenes exhibit important physical properties especially for optoelectronics. Palladium‐catalysed coupling reactions currently represent the most efficient methods to prepare such (hetero)arylated selenophene derivatives. Initially, Stille coupling was the most efficient reaction for the synthesis of these compounds; however, over the last decade, Suzuki coupling has become the most commonly employed. Recently, Pd‐catalysed arylation via the C−H bond activation of selenophenes has proved to be a very convenient alternative method for the preparation of several arylated selenophenes as there is no need to prepare organometallic derivatives. In this Review, the progress and substrate scope in the synthesis of both C2‐ and C3‐arylated selenophenes via Pd‐catalysis are summarized.

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“…5-Bromouracil (Wang, 1959) was transformed to 2,4-dit-butoxypyrimidinebornoic acid (Gronowitz et al, 1986) via 2,4-dichloro-5-bromopyrimidine and 2,4-di-tbutoxypyrimidine. The boronic acid was reacted with 1.5 equivalents of the aryl dibromide with Pd(O)(PPh s )4 as catalyst in dimethoxyethane and sodium bicarbonate solution (1:1), giving the desired compounds (1a-7a) in 48-67% yield after column chromatography (Fig.…”

Section: Chemistrymentioning

confidence: 99%

“…Preparation of the 5-uracil boronic acid (Gronowitz et al, 1986) from 2,4-bis(trimethylsilyloxy)-5-bromopyrimidine had already been attempted. However, this procedure failed due to migration of the 4-trimethylsilyl group.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Various 5-(5″-Substituted-3″-Bromophenyl)-2′-β-Deoxyuridines

Persson

Hörnfeldt

Gronowitz

et al. 1996

Antivir Chem Chemother

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SummaryA series of 5-(511-substituted-311-bromophenyl)-2'-~ deoxyuridines were prepared and investigated for their activity against HCMV and HIV. None of the compounds exhibited any activity against HIV at the highest concentration, 100 J.lg rnr". In the HCMV ELISA assay the EO so and COso values of the 5-(5 11-substituted-3 11-bromophenyl)-2'-deoxyuridines were about 60 J.lg rnr" and 150 J.lg rnr", respectively.

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ChemInform Abstract: Synthesis of Various Thienyl‐ and Selenienylpyrimidines.

Abstract: The title compounds (III), (V) and (VII) are prepared by the Pd(0) ‐catalyzed reaction of appropriately substituted halopyrimidines (II), (IV) and (VI) with the boronic acids (I).

Cited by 15 publications

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Metalation of bromodiazines. Diazines XL

Metalation of bromodiazines. Diazines XL

Access to (Hetero)arylated Selenophenes via Palladium‐catalysed Stille, Negishi or Suzuki Couplings or C−H Bond Functionalization Reaction

Synthesis of Various 5-(5″-Substituted-3″-Bromophenyl)-2′-β-Deoxyuridines

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