Synthesis of 4-Substituted Imidazoles via Palladium-Catalyzed Cross-Coupling Reactions

Jetter, Michele C.

doi:10.1055/s-1998-2069

Cited by 29 publications

(22 citation statements)

References 11 publications

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“…Some examples have also been reported in the literature concerning the introduction of organic groups into the 4‐position of imidazoles via Stille‐type reactions involving the use of 1‐substituted 4‐trialkylstannylimidazoles as organometallic partners 188,202. In 1996, Cliff and Pyne described that the Pd 2 (dba) 3 /AsPh 3 /CuI‐catalyzed reaction of 1‐ethoxymethyl‐4‐trimethylstannylimidazole ( 137 ) with β‐bromostyrene ( E/Z =10:1) results in ( E )‐ and ( Z )‐1‐ethoxymethyl‐4‐(2‐phenylethenyl)imidazole, ( E )‐and ( Z )‐ 139 , in 68 and 12% yield, respectively (Scheme ) 188…”

Section: Functionalization Of Imidazoles At the 4‐positionmentioning

confidence: 99%

“…In 1998, Stille‐ and Negishi‐type reactions involving 4‐tributylstannyl‐1‐tritylimidazole ( 142 ) and 1‐trityl‐4‐imidazolylzinc chloride ( 143 ), respectively, and aryl bromides, iodides and triflates as electrophiles were used by Jetter and Reitz for the high yielding synthesis of 4(5)‐arylimidazoles 202. Representative results of these reactions are illustrated in Scheme .…”

Section: Functionalization Of Imidazoles At the 4‐positionmentioning

confidence: 99%

“…The organometallic reagents 142 and 143 were synthesized by conversion of 4‐iodoimidazole 116c into the corresponding Grignard reagent using EtMgBr in THF or CH 2 Cl 2 as reported in the literature,203 followed by transmetallation with Bu 3 SnCl and ZnCl 2 , respectively 202…”

Section: Functionalization Of Imidazoles At the 4‐positionmentioning

confidence: 99%

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Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Willett

Kawasaki

Amemiya

et al. 2001

Developmental Dynamics

124

101

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The Ikaros gene encodes a transcription factor that, in mice, has been shown to be essential for the correct differentiation of B and T lymphocytes and is expressed in all cells of the lymphoid lineage, including pluripotent hematopoietic stem cells. During development in zebrafish, Ikaros expression begins in lateral mesoderm, and continues in the intermediate cell mass (ICM), which is derived from lateral mesoderm and has been shown to generate primitive hematopoietic precursors. Cells expressing Ikaros were then seen on the ventral side of the dorsal aorta, known to be a location of definitive hematopoietic precursors in birds and mammals. Ikaros-expressing cells were also found in the pharyngeal region, near the forming thymus. Later, such cells were seen in the pronephros, the site of hematopoiesis in adult fish. The timing of appearance of Ikaros-expressing cells suggests that, similar to other vertebrates, lymphocytes in the thymus arise from hematopoietic tissue located near the dorsal aorta or in the ICM.

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Section: Functionalization Of Imidazoles At the 4‐positionmentioning

confidence: 99%

Section: Functionalization Of Imidazoles At the 4‐positionmentioning

confidence: 99%

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Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Willett

Kawasaki

Amemiya

et al. 2001

Developmental Dynamics

124

101

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“…[36] Tristhiazolylpyridin 42, [37] (57), [36] 1,2-(Z)-Methoxycarbonyl-1,3-bis(trimethyl-silyloxy)-1,3-butadien (65), [37] 2-Nitro-6-(2'-tetrahydropyranyloxymethyl)phenyl-brenztrauben-säureethylester (75), [153] 3-Hydrox-ypyridin-5,6-bis(trideutero-methoxycarbonyl)-2-carbon-säuremethylester (97-d 6 ), [241] 131 3-Hydroxypicolinsäuremethylester (100), [278] L-Boc-Thr(TBS)-OH (140), [201] L-FmocThr(TBS)-OH (143), [202] 2'-Bromacetyl-pyridin (161), [219] 6-Brom-3-hydroxypicolinsäure-methyl-ester (204), [267] 4-(Tributyl-stannyl)-1-trityl-1H-imidazol (217), [269] 4,6-Dibrom-3-hydroxy-picolinsäure-diemethylester (228), [278] Dess-Martin-Periodinan, [312] 3-Hydroxypyridin-2,5,6-tricarbonsäure-trimethylester, [37] 3-Meth-oxypicolinsäuremethyl-ester(240) [308] Indol-2-boron-säurepinakolester, [313] Indol-3-boronsäurepinakol-ester, [314] 1H-Pyrrol-3-boronsäure-pinakolester, [315] 1-(Tetrahydro-2H-pyran-2-yl)-1H-pyrazol-5-boronsäurepinakol-ester, [268] Pyrazol-4-boronsäurepinakolester, [314] (R)-2-Azido-3-(tritylthio)-propansäureallyl-ester, [37] PyDOP. [225] Dichlormethan [316] die Sporen wurden anschließend geerntet und in Glycerol gelagert.…”

Section: Synthese Der Nicht Fluorierten Biscarboxamid-ligandenunclassified

Totalsynthese von Nosiheptid

Wojtas

Riedrich

et al. 2016

Angewandte Chemie

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Eine Totalsynthese des bismakrocyclischen Thiopeptidantibiotikums Nosiheptid gelang durch den Aufbau einer voll funktionalisierten linearen Vorstufe und konsekutive Makrocyclisierungen. Schlüsselmerkmale waren eine kritische Makrothiolactonisierung und eine milde Entschützungsstrategie für den 3‐Hydroxypyridin‐Kern. Der Naturstoff war mit isoliertem authentischem Material im Hinblick auf spektroskopische Daten und antimikrobielle Aktivität identisch.

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“…Coupling of either the 4-imidazo zinc reagent 12 or the 4-(tributylstannyl)imidazole (not shown) gave alkene 13 (78% when using zincate 12). 8 * To whom correspondence should be addressed: Allen B. Reitz. …”

mentioning

confidence: 99%

α₂ Adrenoceptor Agonists as Potential Analgesic Agents. 2. Discovery of 4-(4-Imidazo)-1,3-dimethyl-6,7-dihydrothianaphthene as a High-Affinity Ligand for the α_2D Adrenergic Receptor

et al. 2000

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Pages 765-768. Due to an error at the final stage of transferring the ASAP web version (published February 17, 2000) to the printed version, Scheme 4 and Tables 1 and 2 were inadvertently deleted. Unfortunately consideration of this data is essential for interpreting the other parts of the published paper; therefore, the communication is printed here in its entirety. Received November 15, 1999 Introduction. The treatment of pain continues to be the subject of considerable pharmaceutical and clinical research. 1 R 2 Adrenoceptor agonists are intriguing because they produce clinically effective analgesia that is devoid of opioid-related side effects. 2 The R 2 adrenergic agonist clonidine (1) is prescribed for the epidural treatment of severe pain, and the R 2 agonist dexmedetomidine (2) is used in veterinary practice and for humans in several countries outside the United States. 3 The primary site of antinociceptive action for R 2 adrenergic analgesia is in the dorsal horn of the spinal cord. 2a R 2 Adrenergic receptors are localized largely in the presynaptic membrane, and activation of these receptors inhibits the release of pain-inducing neurotransmitters such as substance P, glutamic acid, and CGRP. We have recently reported the potent R 2 adrenergic receptor affinity and analgesic activity associated with (imidazomethyl)oxazoles and -thiazoles, such as 3 . 4 In addition, we have investigated a large number of (imidazomethyl)thiophenes, such as 4, that have a similar biological profile. 5 Analyzing the preferred conformations of 4 by molecular modeling revealed significant torsional freedom for rotation of the two single bonds between the imidazole and thiophene. To restrict the rotation of this molecule, we extended and combined the 2-ethyl substituent with the bridging carbon atom to obtain the (imidazo)thianaphthene chemical series (e.g. 8 and 9, Scheme 1). These compounds are potent R 2 adrenergic receptor ligands, and certain members of the series are very active in animal models of antinociception. 4-(4-Imidazo)-6,7-dihydrothianaphthene (14) has a favorable biological profile in vivo and is a prototype for this class of analgesic agents.Chemistry. Several complementary methods were used to prepare the (imidazo)thianaphthenes. Reaction of thienyl ketone 5 6 with the Grignard reagent 7 derived from 4-iodo-1-tritylimidazole (6) gave alcohol 7 (84%; Scheme 1). This material was either treated with HCl in MeOH to yield unsaturated derivative 8 (20%) or reduced to fully saturated 9 by hydrogenation over palladium on carbon (29%). Although this method was used for the preparation of 14 and 15, we also developed a strategy involving vinyl triflate coupling as shown in Scheme 2. Thienyl ketone 10 was converted to vinyl triflate 11 in 90% yield by using triflic anhydride and a hindered pyridine base. Coupling of either the 4-imidazo zinc reagent 12 or the 4-(tributylstannyl)imidazole (not shown) gave alkene 13 (78% when using zincate 12). 8 * To whom correspondence should be addressed: Allen B. Reitz. M...

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Synthesis of 4-Substituted Imidazoles via Palladium-Catalyzed Cross-Coupling Reactions

Cited by 29 publications

References 11 publications

Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Totalsynthese von Nosiheptid

α₂ Adrenoceptor Agonists as Potential Analgesic Agents. 2. Discovery of 4-(4-Imidazo)-1,3-dimethyl-6,7-dihydrothianaphthene as a High-Affinity Ligand for the α_2D Adrenergic Receptor

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Synthesis of 4-Substituted Imidazoles via Palladium-Catalyzed Cross-Coupling Reactions

Cited by 29 publications

References 11 publications

Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Ikaros expression as a marker for lymphoid progenitors during zebrafish development

Totalsynthese von Nosiheptid

α2 Adrenoceptor Agonists as Potential Analgesic Agents. 2. Discovery of 4-(4-Imidazo)-1,3-dimethyl-6,7-dihydrothianaphthene as a High-Affinity Ligand for the α2D Adrenergic Receptor

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α₂ Adrenoceptor Agonists as Potential Analgesic Agents. 2. Discovery of 4-(4-Imidazo)-1,3-dimethyl-6,7-dihydrothianaphthene as a High-Affinity Ligand for the α_2D Adrenergic Receptor