Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• provided the desired carboamination product 164. By using methyl cinnamate derivatives, the reactions were highly diastereoselective for the formation of 1,2-anti carboamination products. Notably, the Ritter reaction was found to be the origin of diastereoselectivity on the basis of a density functional

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• was further demonstrated by a series of successful derivatizations of the cyano-substituted oxindole 8a. For instance, after the Ritter reaction, 8a was smoothly converted to N-tert-butylated acetamide 12 in 96% yield (Scheme 6b). A modified Witte–Seeliger reaction led to the formation of oxazoline 13

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• -amidotetrahydropyran derivative 106 was also synthesized from homoallylic alcohol 104 and an aldehyde 105 using a combination of cerium chloride and acetyl chloride following a Prins–Ritter reaction sequence (Scheme 24) [58]. 10 mol % cerium chloride was used as a reaction promotor, which dramatically improved the

• centrolobine synthesis. Yadav and co-workers’ strategy for the synthesis of THP. Yadav and co-workers’ Prins–Ritter reaction sequence for 4-amidotetrahydropyran. Yadav and co-workers’ strategy to prelactones B, C, and V. Yadav and co-workers’ strategy for the synthesis of (±)-centrolobine. Loh and co-workers

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• ligands are prepared in two steps from readily available 1,2-O-isopropylidene protected β-D-fructopyranoses by the BF3·OEt2-promoted Ritter reaction with 2-bromobenzonitrile to construct the oxazoline moiety followed by Ullmann coupling of the resulting aryl bromides with diphenylphosphine. Both steps

• proceeded mostly in good to high yields (57–86% for the Ritter reaction and 35–89% for the Ullmann coupling). The Ritter reaction gave two anomers, which could be separated by column chromatography. The prepared ligands showed promising results (er of up to 84:16) in Tsuji–Trost reactions with diphenylallyl

• acetate as model substrate. Keywords: Fürst–Plattner rule; oxazoline; Ritter reaction; Tsuji–Trost reaction; Ullmann coupling; Introduction The vast majority of biologically active compounds like vitamins and natural products occur as single enantiomers in nature. Usually only one enantiomer generates

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• nearly 90% yields for α-amino esters in 90–120 min (Scheme 18). The Ritter reaction is another significant carbon–nitrogen (C–N) bond forming reaction in the synthesis of amides [86]. Generally, a nitrile and a tertiary alcohol in presence of a strong acid react to create amides. Major drawbacks

• associated with this method are the requirement of stoichiometric amounts of strong acid, higher temperature, narrower substrate scope, etc. In 2015, Gredičak and co-workers developed a milder version of the Ritter reaction under mechanomilling conditions. Using 0.5 equivalents of H2SO4, amides were isolated

• acids [78]. Mechanochemical amidation reaction from aromatic aldehydes and N-chloramine [79]. Mechanochemical CDC between benzaldehydes and benzyl amines [81]. Mechanochemical protection of -NH2 and -COOH group of amino acids [85]. Mechanochemical Ritter reaction [87]. Mechanochemical synthesis of

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• investigated the activation of a C–Br bond by novel halogen-bond donors L16 and L17 [82]. The authors synthesized compounds L16 and L17 as well as some other halogen bond donors and tested their ability to promote the Ritter reaction of (bromomethylene)dibenzene (Scheme 16). The stoichiometric amounts of L16

• produced in this reaction will eventually form chlorotrialkylsilane, which does not inhibit the catalyst. As a result, catalytic amounts of neutral HBDs L19–L21 were found to promote this transformation at 10–20 mol % catalyst loading. Unlike the Ritter reaction study summarized in Scheme 16, the activity

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• the C=C derived O-nitrates focuses on a report by Scheinbaum and Dines who established that alkenes in the presence of acetonitrile and 22 undergo a Ritter reaction affording vicinal nitro acetamido species [29]. Silver nitrate reacts with alkyl, benzyl or acyl halides affording the corresponding

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group. Keywords: fructose; oxazoline; riboside; Ritter reaction; spiro; Introduction 2-Oxazolines represent a unique class of 5-membered heterocyclic

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• heterolysis of the substrate and subsequent ionic Ritter reaction. This notion was supported by our experiments performed in DMSO where a higher portion of the photocatalyst resides in the active EY3 and EY4 states. Following an otherwise identical protocol, irradiation at 535 nm resulted in the formation of

A Lewis acid-promoted Pinner reaction

• Dominik Pfaff,
• Gregor Nemecek and
• Joachim Podlech

Beilstein J. Org. Chem. 2013, 9, 1572–1577, doi:10.3762/bjoc.9.179

• esters; Lewis acids; Pinner reaction; Ritter reaction; Introduction In 1877 Pinner and Klein discovered the proton-induced imidate syntheses [1][2]. They passed anhydrous gaseous hydrogen chloride through a mixture of isobutyl alcohol and benzonitrile. A crystalline product precipitated, which they

• acid-promoted Pinner reaction. Synthesis of monaspilosin. Proposed mechanism of the trimethylsilyl triflate-promoted Ritter reaction. Selection of optimization experiments. Variation of nitriles and alcohols.a Carboxamide formation in a Pinner-type reaction.a Supporting Information Supporting

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• this process through a Ritter reaction between cation 13 and the solvent acetonitrile (Scheme 9). Hypothetically, both the Lewis acidity and oxidizing ability of CuX2 should depend on the basicity of the counter ion (X−: conjugate base of HX). Based on the acidity order HX, TfOH > HCl > AcOH ~ 2-ethyl

Two-directional synthesis as a tool for diversity-oriented synthesis: Synthesis of alkaloid scaffolds

• Kieron M. G. O’Connell,
• Monica Díaz-Gavilán,
• Warren R. J. D. Galloway and
• David R. Spring

Beilstein J. Org. Chem. 2012, 8, 850–860, doi:10.3762/bjoc.8.95

• α,β-unsaturated ester functionality. This sequence provided the desired N-Boc-aminoalkenes in respectable overall yields of 38–56%. Compound 4 was prepared in a four-step sequence from the requisite phenyldialkyl alcohol. Ritter reaction with chloroacetonitrile followed by cleavage of the resulting