Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• Zhang Dongxu Department of Fire Protection Engineering, China Fire and Rescue Institute, Beijing 102202, P. R. of China 10.3762/bjoc.19.127 Abstract Nitrogen-containing organofluorine derivatives, which are prepared using fluorinated building blocks, are among the most important active fragments

• . Keywords: acylhydrazones; difluoromethylation; dihydropyridazine; fluorinated building blocks; hydrazones; imidazolidines; pyrazoles; pyrazolidines; pyrazolines; trifluoromethylation; Introduction The introduction of fluorine into pharmaceuticals, agrochemicals, and materials can significantly enhance

• as fluorinated building blocks for the synthesis of difluoromethylated pyrazole derivatives by such [3 + 2] cycloaddition reactions [73][84][85] (Scheme 13). These studies therefore emphasize that fluoromethylated nitrile imines are versatile building blocks for [3 + 2] and [3 + 3] cycloaddition

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• with an organic azide. A relatively wide range of 1,4,5-trisubstituted-1,2,3-triazoles was obtained in 30–70% yields with high regioselectivity and modest functional group tolerability. This work demonstrates that gem-difluoroalkenes can serve as versatile fluorinated building blocks in lieu of alkynes

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• provide the reader a nice overview. Since reviews dealing with transition-metal-catalyzed functionalization of compounds by C–H bond activation with fluorinated reagents [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77] and vinylic, allylic or propargylic fluorinated building blocks

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• applications [16][17][18][19][20][21], etc [22]. The use of fluorinated building blocks is a very convenient approach and in many cases represents an indispensable alternative to late-stage fluorinations in the preparation of such unique materials [23]. The Diels–Alder reaction is considered a versatile and

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

• Benjamin Jeffries,
• Zhong Wang,
• Robert I. Troup,
• Anaïs Goupille,
• Jean-Yves Le Questel,
• Charlene Fallan,
• James S. Scott,
• Elisabetta Chiarparin,
• Jérôme Graton and
• Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

• (Figure 4), using the directly comparable isobutanol, cyclopropylmethanol and 3-oxetanylmethanol scaffolds. All compounds are either commercially available or are easily synthesized from available fluorinated building blocks. In addition, comparison of lipophilicities of relevant linear butanol

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• transformations to yield more complex biologically active molecules. Despite the increasing availability of fluorinated building blocks and methodologies to incorporate fluorine in compounds with biological interest, there have been few significant advances focused on the fluoro-Pauson–Khand reaction, both in the

• most profound influence [10][11][12]. Regarding the development of new synthetic methodologies for the preparation of such molecules, these can be divided in two main categories: fluorination reactions [13][14][15][16] and the use of fluorinated building blocks [17]. The difference between them is that

• that will be discussed in this review belongs to the fluorinated building blocks category. More specifically, the participation of fluorine-containing olefins and alkynes in the Pauson–Khand cyclization, with a special focus on the intramolecular version using fluorinated enynes, which will be

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• modern pharmaceuticals [1][2][3][4][5][6] and agrochemicals [7] contain at least one fluorine atom [8][9][10][11][12][13][14][15]. One of the approaches for their synthesis is the use of small fluorinated building blocks which avoids the often cumbersome regioselective fluorination at a later synthetic

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• enantiomer (S)-63a to be achieved in 67% yield and 86% ee starting from the corresponding imine 60a (Scheme 24). This convenient methodology constituted a novel and simple approach to chiral fluorinated building blocks. In 2016, Pedro and Vila envisioned the first use of cyclic imines, such as

The synthesis of the 2,3-difluorobutan-1,4-diol diastereomers

• Robert Szpera,
• Nadia Kovalenko,
• Kalaiselvi Natarajan,
• Nina Paillard and
• Bruno Linclau

Beilstein J. Org. Chem. 2017, 13, 2883–2887, doi:10.3762/bjoc.13.280

• Robert Szpera Nadia Kovalenko Kalaiselvi Natarajan Nina Paillard Bruno Linclau Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom 10.3762/bjoc.13.280 Abstract The diastereoselective synthesis of fluorinated building blocks that contain chiral fluorine

• drugs/agrochemicals, as well as materials [2][3][4][5][6]. Many methods exist for the stereoselective introduction of the C–F group [7][8][9][10][11]. An alternative and often time-efficient approach is the use of fluorinated building blocks, where fluorine is introduced as part of a carbon containing

• fragment, sometimes also bearing other functionality [12][13]. The development of novel fluorinated building blocks is therefore of interest, particularly those that can be synthesised conveniently on a multigram scale. Interestingly, the majority of currently commercially available fluorinated building

Selectively fluorinated cyclohexane building blocks: Derivatives of carbonylated all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane

• Mohammed Salah Ayoup,
• David B. Cordes,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 2671–2676, doi:10.3762/bjoc.11.287

• derivatisation and facilitate the incorporation of the facially polarised all-cis-1,2,4,5-tetrafluorocyclohexane motif into more advanced molecular scaffolds. Keywords: cyclohexane carbonylation; fluorine containing building blocks: organofluorine chemistry; Introduction Selectively fluorinated building blocks

Syntheses of fluorooxindole and 2-fluoro-2-arylacetic acid derivatives from diethyl 2-fluoromalonate ester

• Antal Harsanyi,
• Graham Sandford,
• Dmitri S. Yufit and
• Judith A.K. Howard

Beilstein J. Org. Chem. 2014, 10, 1213–1219, doi:10.3762/bjoc.10.119

• processes. Keywords: fluorinated building blocks; fluoroarylacetic acid; fluoromalonate; fluorooxindole; organo-fluorine; selective fluorination; Introduction Since 1954, when Fried and Sabo observed that the incorporation of a fluorine atom into a corticosteroid derivative led to valuable enhanced

• transformations involving all the reactions and techniques available to synthetic organic chemists [10][11][12][13]. Of course, the success of an ‘early stage’ fluorination approach depends on the availability of a range of appropriately functionalised, fluorinated building blocks and the establishment of

• availability of synthetic procedures for the preparation of various 2-fluoro-1,3-dicarbonyl systems [20][21][22][23][24][25][26][27], there is, surprisingly, only a relatively limited number of publications that report the use of such potentially useful fluorinated building blocks for the synthesis of more

One-pot cross-enyne metathesis (CEYM)–Diels–Alder reaction of gem-difluoropropargylic alkynes

• Santos Fustero,
• Paula Bello,
• Javier Miró,
• María Sánchez-Roselló,
• Günter Haufe and
• Carlos del Pozo

Beilstein J. Org. Chem. 2013, 9, 2688–2695, doi:10.3762/bjoc.9.305

• CEYM reaction, ethylene does not incorporate into the product but intercepts the secondary metathesis pathways avoiding the formation of secondary products during the process [17][18]. Among organic fluorine compounds, propargylic fluorides constitute a relevant class of fluorinated building blocks

• -octadiene as an internal source of ethylene [29]. Following our ongoing interest in the use of these fluorinated building blocks, we decided to evaluate the CEYM reaction of several difluoropropargylamides and ketones in combination with a Diels–Alder reaction under Mori´s conditions, in order to compare

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• /deprotection chemistry, and in some cases, the availability of the precursor sugar. Some less common sugars are expensive and available in limited quantities. The alternative approach involves de novo stereodivergent synthesis, which elaborates small fluorinated building blocks using the reactions of modern

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• different fluorinated building blocks was demonstrated by the easy ring opening of these intermediates with NaBH4 and NiCl2, yielding the corresponding trifluoromethylated γ-amino alcohol. Example of bioactive molecules bearing the 2-isoxazoline nucleus. Dimerization and isomerization products from nitrile

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• their intrinsic tendency to adopt this secondary structure (i.e. their α-helix propensity) was shown to be considerably reduced when compared to their canonical analogues [8][9]. Thus, if enhanced thermal stabilities of helical assemblies containing aliphatic fluorinated building blocks have been

Novel synthesis of pseudopeptides bearing a difluoromethyl group by Ugi reaction and desulfanylation

• Jingjing Wu,
• Hui Li and
• Song Cao

Beilstein J. Org. Chem. 2011, 7, 1070–1074, doi:10.3762/bjoc.7.123

• building blocks have been used in the Ugi four-component reaction to construct a fluorinated compound library [22][23][24][25]. Our group has always been interested in developing efficient methods for the preparation of difluoromethyl-containing compounds through multicomponent reactions [26][27][28][29

• triglyceride transfer protein (MTP) and useful for the treatment of obesity and atherosclerosis (Figure 1) [20]. Among the protocols for the preparation of pseudopeptide derivatives, the Ugi four-component reaction offers significant advantages over conventional linear-step synthesis [21]. Various fluorinated

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• active methylene derivatives has attracted considerable attention particularly in the field of medicinal chemistry [5][6]. One of the major interests in our group has focused on developing new fluorination reagents or fluorinated building blocks for preparation of fluorine-substituted compounds [7][8][9