Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• of some of the products was investigated and selected synthetic transformations of the obtained tetrahydrofuro[3,2-c]pyridines were shown. Keywords: acid hydrolysis; 1,4-diketone; tetrahydrofuro[3,2-c]pyridines; Paal–Knorr reaction; Pictet–Spengler reaction; Introduction Hydrogenated furo[3,2-c

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• last decade, the optical activity of arylpyrroles has been explored by optical resolution of racemates using chiral resolving agents or chiral column chromatography [81]. Although Zhang et al. developed the first catalytic asymmetric Paal–Knorr reaction for accessing highly enantioenriched axially

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• pyrrole derivatives: i) Knorr reaction: the condensation of α-aminoketones or α-amino esters in the presence of zinc powder and sodium acetate; ii) Paal–Knorr reaction: the condensation of 1,4-dicarbonyl compounds and amines, catalyzed by formic acid in anhydrous alcohol; iii) Hantzsch reaction: the

Low-budget 3D-printed equipment for continuous flow reactions

• Jochen M. Neumaier,
• Amiera Madani,
• Thomas Klein and
• Thomas Ziegler

Beilstein J. Org. Chem. 2019, 15, 558–566, doi:10.3762/bjoc.15.50

• ]. Unfortunately, the synthetic steps for the glycoside preparation could not be combined in a multistep reaction, due to clogging of the packed bed reactor, most likely due to the formation of silver bromide during the Koenigs–Knorr reaction. No such clogging was observed when the column was packed with Fetizon’s

• synthesis of acetobromo-α-D-glucose 2. b) Photograph of a typical setting for continuous flow reaction. Preparation of acetobromo-α-D-glucose 2. Flow Koenigs–Knorr reaction to methyl glycoside 3 with silver triflate. Preparation of glycosyl donor 5. Two-step glycosylation reactions starting from pyranose 3

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• the reference compound, cisplatin. Keywords: antiproliferative activity; Knorr reaction; microwave; pyrazol-5-ones; steroids; Introduction 17-exo-Heterocyclic androstanes with five or six-membered heterocyclic rings connected directly to C-17 of the sterane core represent a remarkable subclass of

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• demanding chiral biaryldiols with excellent enantioselectivities [23]. Recently, highly atropselective synthesis of arylpyrroles by the catalytic asymmetric Paal–Knorr reaction for the synthesis of enantiomerically pure arylpyrroles was presented by Tan [25]. Also as an alternative to palladium couplings

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• –Knorr cyclization, thus affording tricyclic thieno[2,3-b]indoles. Keywords: aldol-crotonic condensation; isatin; Lawesson’s reagent; methyl ketones; Paal–Knorr reaction; thieno[2,3-b]indole; Introduction 8H-Thieno[2,3-b]indole is a fused heterocyclic system, which has attracted a considerable

• indolin-2-ones 11. Compounds 11 bearing the fragment of 4-oxobutyramides (1,4-dicarbonyl derivatives) can be cyclized into thieno[2,3-b]indoles by using the Paal–Knorr reaction with such thionation agents, as P4S10 or Lawesson’s reagent. This four-step route to thieno[2,3-b]indoles via the formation of

• means of the Paal–Knorr reaction. Compound 9a has also been treated with the Lawesson's reagent in toluene to give the title product 12a via intermediacy of 10a in a low 10% yield, based on the starting isatin 7a (Path A). Also the one-pot synthesis (Path D) of compound 12a has been realized through

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57