Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• the corresponding pyrazolone derivatives, thereby providing access to both bis(pyrazolyl) and bis(pyrazolonyl)methanes. Enaminones 81 can be generated as intermediates by condensation of 1,3-dicarbonyl compounds and DMF-dimethylacetal (DMFDMA, 79). The reaction is catalyzed by the solvent 2,2,2

Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal

• Antonio Arcadi,
• Sandro Cacchi,
• Giancarlo Fabrizi,
• Francesca Ghirga,
• Antonella Goggiamani,
• Antonia Iazzetti and
• Fabio Marinelli

Beilstein J. Org. Chem. 2018, 14, 2411–2417, doi:10.3762/bjoc.14.218

• reaction of o-(o-aminophenylethynyl) trifluoroacetanilides with Ar–B(OH)2 afforded 2-(o-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo[1,2-c]quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is

• different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar–I, Ar–Br and ArN2+BF4−, that afforded 12-arylindolo[1,2-c]quinazolin-6(5H)-ones. Moreover, 12-unsubstituted indolo[1,2-c]quinazolines can be obtained both by reacting 2-(o-aminophenyl)indoles with DMFDMA

• or by sequential Pd-catalyzed reaction of o-(o-aminophenylethynyl)aniline with DMFDMA. Keywords: arylboronic acids; DMFDMA; indoles; indoloquinazolines; quinazolines; Introduction Indoloquinazoline derivatives constitute an important class of compounds which exhibit a wide range of biological

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• of 5-amino-4-cyanopyrazole 208 with N,N-dimethylformamide dimethyl acetal (DMFDMA) in acetonitrile at reflux temperature. Amidines 219 were condensed with appropriate 2-amino-5-subsitituted-1,3,4-thiadiazoles 220 under microwave irradiation in acetic acid for the generation of the desired pyrazolo

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• , obtained via Au-catalyzed Meyer–Schuster rearrangement. Assembly of 5-oxygenated bisindolylpentenones. DMB: 3,4-dimethoxybenzyl, DMFDMA: N,N-dimethylformaldehyde dimethyl acetal. Benzylic oxidation as side reaction of DMB removal. Hydroxyalkylation of N-protected indoles with β-cyclocitral and SnCl4

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• -Iodoindole (4) was prepared from 1-iodo-4-methyl-3-nitrobenzene (3, accessible from the corresponding nitroaniline via Sandmeyer reaction) via the Batcho–Leimgruber protocol employing dimethylformamide dimethyl acetal (DMFDMA) and TiCl3 in one step. It should be noted that, after initial column filtration of

Organobase-catalyzed three-component reactions for the synthesis of 4H-2-aminopyrans, condensed pyrans and polysubstituted benzenes

• Moustafa Sherief Moustafa,
• Saleh Mohammed Al-Mousawi,
• Maghraby Ali Selim,
• Ahmed Mohamed Mosallam and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2014, 10, 141–149, doi:10.3762/bjoc.10.11

• produced by a sequence including an initial condensation reaction of the 2-amino-4H-pyrans 9a and 9b with dimethylformamide dimethylacetal (DMFDMA) to yield the amidine-substituted derivatives 32a and 32b. Stirring solutions of these substances in refluxing AcOH/NH4OAc gave the respective pyranopyrimidines

• reacts with DMFDMA to form amidine 38, which undergoes cyclization in refluxing AcOH/NH4OAc to form the 1-amino-pyrrolo[3,4-f]quinazoline 39. We also found that 37a reacts with hydroxylamine hydrochloride in ethanolic sodium acetate solution to form isoindolone derivative 40 (Scheme 11 and Figure 13

Enaminones in a multicomponent synthesis of 4-aryldihydropyridines for potential applications in photoinduced intramolecular electron-transfer systems

• Nouria A. Al-Awadi,
• Maher R. Ibrahim,
• Mohamed H. Elnagdi,
• Elizabeth John and
• Yehia A. Ibrahim

Beilstein J. Org. Chem. 2012, 8, 441–447, doi:10.3762/bjoc.8.50

• prepared by various methods, for example, 1 is readily obtained in excellent yield by the condensation of different methylketones with dimethylformamide dimethylacetal (DMFDMA) [16][17]. In this work we investigated the potential utility of 1 in a three-component synthesis of dihydropyridines (DHP) (Scheme

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

• Kamal Usef Sadek,
• Ramadan Ahmed Mekheimer,
• Tahany Mahmoud Mohamed,
• Moustafa Sherief Moustafa and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2012, 8, 18–24, doi:10.3762/bjoc.8.3

• (DMFDMA) in DMF at 150 °C under controlled microwave heating afforded regioselectively 8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-ones 6 rather than the corresponding dihydropyrazolo[5,1-b]quinazolin-8(5H)-ones 4. Keywords: aminopyrazoles; dimedone; DMFDMA; regioselectivity; Introduction Several

• investigation concerning the regioselectivity in multicomponent reactions of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal (DMFDMA) under controlled microwave heating. We began this study by treating 5-amino-3-methylpyrazole (1a) and dimedone (2a) with DMFDMA (3) in DMF under

• ) in DMF under microwave heating at 150 °C for 10 min to afford 5. Subsequently, treating compound 5 with DMFDMA (3), under the same experimental conditions, gave compound 6a in excellent yield (Scheme 1 and Table 1). Furthermore, the structures of compounds 5 and 6a were unambiguously confirmed by

An easy synthesis of 5-functionally substituted ethyl 4-amino- 1-aryl- pyrazolo- 3-carboxylates: interesting precursors to sildenafil analogues

• Said A. S. Ghozlan,
• Khadija O. Badahdah and
• Ismail A. Abdelhamid

Beilstein J. Org. Chem. 2007, 3, No. 15, doi:10.1186/1860-5397-3-15

• -arylhydrazononitriles 1a-c react readily with chloroacetonitrile, ethyl chloroacetate, and with phenacyl chloride to give 4-aminopyrazoles 4a-e. The pyrazolo[4,3-d]pyrimidine derivatives 7 and 10 are synthesized via reaction of the aminopyrazole 4b with phenylisothiocyanate and DMFDMA/NH4OAc respectively. Background

• derivative 8. (cf. Scheme 2) Compound 4b condensed with dimethylformamide dimethylacetal (DMFDMA) to yield the enamine 9. The 1H NMR spectrum indicated two distinct singlets at ä 2.97 and 3.05 ppm for the N,N-dimethylamino protons which mean that the two methyl groups are magnetically nonequivalent, as to be

2-Arylhydrazononitriles as building blocks in heterocyclic synthesis: A novel route to 2-substituted- 1,2,3-triazoles and 1,2,3-triazolo[4,5-b]pyridines

• Saleh M. Al-Mousawi and
• Moustafa Sh. Moustafa

Beilstein J. Org. Chem. 2007, 3, No. 12, doi:10.1186/1860-5397-3-12

• [4,5-b]pyridine 8. Treatment of acetyl derivative 6 with DMFDMA gave enaminone 9. The enaminone 9 was coupled with benzenediazonium chloride to yield phenylazo-1,2,3-triazolo [4,5-b]pyridine 10. Trials to convert compound 14 into 1,2,3-triazolo [4,5-d]pyrimidine 15 via refluxing in AcOH/NH4OAc failed

• triazolopyridine 8, thus confirming that the aminofunction and the acetyl function are adjacent. Moreover, reacting 6 with dimethylformamide dimethylacetal (DMFDMA) afforded the cis enaminone 9 (J = 8 Hz) despite the fact that secondary enaminones have been established to prefer adopting the trans configuration