Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• the chemistry of the sumanene and its congeners, quite recently the same group has also prepared sumanene-based carbene 60 starting from monosumanenone 38 by reacting it with hydrazine hydrate to provide the corresponding hydrazone 58 which on further oxidation with MnO2 followed by irradiation using

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• (Scheme 1) [7] such as water or alcohol [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], primary or secondary amines [23][24][25][26][27][28], or hydrazine [29][30][31]. These reactions are synthetically useful since gold catalysis is characterized by a good functional group tolerance for

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• ) group under basic conditions followed by peracetylation afforded compound 10 on a ≈150 g scale. The regioselective anomeric deacetylation with hydrazine and reprotection of the anomeric hydroxy group as tert-butyldimethylsilyl ether (TBS) led to compound 12. Compound 12 was then treated with sodium

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• of the intermediately formed imine to the Michael acceptor (Scheme 3). We then investigated the synthesis of cinnoline derivatives by mixing the diketone 5a and hydrazine monohydrate under various conditions (Table 2). We first investigated the reactivity in ethanol, as a protic solvent, at room

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• developed, starting from sulfonyl hydrazines in place of sulfonyl chlorides. In this case, the RuII-based photocatalyst was able to reduce tert-butyl peroxybenzoate, triggering the release of a tert-butoxyl radical. This was in turn able to oxidize the hydrazine, allowing the liberation of the desired

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

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

• hydrazine on the more reactive carbon atom of the fluoroenolate in a Michael-type addition. The cyclization did not require a deprotonation of the RNH moiety. Conclusion In summary, a synthesis of fluorinated pyrimidines under mild conditions using fluoroenolate 8 and amidines in a cyclocondensation was

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• to a dichloromethane solution of 2,6-aminopyridine (110) afforded the multidentate ligand 111 in an excellent yield (97%) within 2 h. This in contrast to a method reported by Gaw et al. where the reaction took several days in diethyl ether [104]. Phosphine hydrazine P–N and N–N bonds are labile and

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• subjected to a sequence of reactions consisting of (i) reductive transformation of the azido group into an acetamido group by the treatment with thioacetic acid [34]; (ii) transformation of the N-phthalimido group into acetamido group using hydrazine hydrate followed by selective N-acetylation [35]; (iii

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• , 126.2, 123.5, 123.1, 91.5, 56.3, 55.8; HRESIMS (m/z): [M + H]+ calcd for C15H1579Br2N2O3, 428.9444; found, 428.9448. tert-Butyl (E)-2-(3-bromo-5-((2,4,6-trimethoxyphenyl)diazenyl)phenyl)-1-(4-cyanophenyl)hydrazine-1-carboxylate (16a): In a nitrogen-filled glovebox, an oven-dried Schlenk tube was charged

• with a 1.61 M solution of P(t-Bu)3 (395 µL, 636 µmol, 15 mol %) in dry toluene. All following operations were carried out in a fume hood under Schlenk conditions. tert-Butyl 1-(4-cyanophenyl)hydrazine-1-carboxylate (1.00 g, 4.25 mmol, 1.00 equiv), 15 (1.82 g, 4.24 mmol, 1.00 equiv), Pd(OAc)2 (144 mg

• C27H2879BrN5O5Na, 604.1166; found, 604.1167. tert-Butyl (E)-2-(3-bromo-5-((2,4,6-trimethoxyphenyl)diazenyl)phenyl)-1-(4-methoxyphenyl)hydrazine-1-carboxylate (16b): In a nitrogen-filled glovebox, an oven-dried Schlenk tube was charged with P(t-Bu)3 (155 µL, 628 µmol, 15 mol %). All following operations were

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• protecting groups, whereby Fmoc was cleaved by piperidine (20 vol % in DMF), while Lev was removed using hydrazine acetate. Iterative cycles continued until the desired structure was obtained. The oligosaccharide products were cleaved from the solid support using a flow UV photoreactor, followed by a two

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• /C (0.0145 g) was refluxed in dry ethanol (10 mL) for 1 h. After dropwise addition of hydrazine monohydrate (0.30 mL), the reaction mixture was refluxed overnight. After filtration of Pd/C and concentrating the filtrate to dryness, the resulting white solid (0.320 g) was identified as 4-amino-4’,4

• mmol) and Pd/C (0.0145 g) in dry ethanol (10 mL) was refluxed for 1 h. After dropwise addition of hydrazine monohydrate (0.30 mL), the reaction mixture was refluxed overnight. After filtration and concentrating the filtrate to dryness, the resulting white solid (0.320 g) was identified as 4-amino-4’,4

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• state, as envisioned. Possible reasons could be assigned to substituent effects as demonstrated by Simeth et al. [62]. As recently reported by Schehr et al., reducing agents like DTT, used to prevent enzyme oxidation in crystallization mixtures or in vitro assays, can reduce azo dyes to hydrazine

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• conditions (catalytic palladium on carbon and hydrazine hydrate) was found to be the most efficient method for obtaining monoaminocalix[4]arene 10 in essentially quantitative yields (Scheme 3). The azide-Sandmeyer reaction on monoaminocalix[4]arene 10 was then attempted using sodium nitrite and p

Synthesis and conformational preferences of short analogues of antifreeze glycopeptides (AFGP)

• Małgorzata Urbańczyk,
• Michał Jewgiński,
• Joanna Krzciuk-Gula,
• Jerzy Góra,
• Rafał Latajka and
• Norbert Sewald

Beilstein J. Org. Chem. 2019, 15, 1581–1591, doi:10.3762/bjoc.15.162

• anhydride (50 equiv), DIEA (12.5 equiv), 1-hydroxybenzotriazole (HOBt,1 equiv) in DMF at room temperature for 40 min. Subsequently, the carbohydrate moieties were deacetylated using 1.0 M hydrazine in dry THF at room temperature for 2 hours. The peptides were cleaved from the resin by treatment with 7–10

• -GalNAc)-OH (1 equiv), HOAt (2.25 equiv), HATU (2.8 equiv), DIEA (2.75 equiv), DMF, rt, 3 h; d. Fmoc-L-Ala-OH∙H2O (4 equiv), TBTU (4 equiv), DIEA (4 equiv), DMF, rt, 2 h; e. Ac2O (50 equiv), DIEA (12.5 equiv), HOBt (1 equiv), DMF, rt, 40 min; f. 1.0 M hydrazine in THF, rt, 2 h; g. 7–10% TFA in DCM, rt

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• of the formed hydrazine (16%). The unprotected ethynyldiazocine 8 was deprotonated with potassium hydroxide and connected to the central carbon atom of the TATA platform 9 (synthesized according to Laursen and Krebs [28]) to obtain target para-diazocine mounted on the octyl-substituted TATA platform

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• ][51][52], pyrimidines [48][49], and 5-acylpyrazoles [48][49]. The latter 5-acylpyrazole arose after work-up from the three-component AA–cyclocondensation synthesis employing Boc-hydrazine as a binucleophilic hydrazide substrate. Based on our attempts to isolate potential 1,5-diacylpyrazole precursors

• intermediate 5a could be a 1,5-diacylpyrazole. However, upon performing the terminal cyclization step starting from 1,4-diphenylbut-3-yne-1,2-dione (3a) and Boc-hydrazine (4a) under identical conditions 1-Boc-5-benzoyl-5-hydroxypyrazoline was isolated in 83% yield (Scheme 3). The molecular structure was

• . Cyclization of 1,4-diphenylbut-3-yne-1,2-dione (3a) and Boc-hydrazine (4a) to give intermediate 5a. Model reaction for optimizing the activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazoline 5b. One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines 5

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• yields. Overall, five different components are incorporated in the reaction sequence, whereas acid chlorides, anhydrides, hydrazine, etc., could also be employed in the post-MCR cyclization [44]. The library of steroidal heterocycles was tested against oxidative stress and neuroinflammation due to

Insertion of [1.1.1]propellane into aromatic disulfides

• Robin M. Bär,
• Gregor Heinrich,
• Martin Nieger,
• Olaf Fuhr and
• Stefan Bräse

Beilstein J. Org. Chem. 2019, 15, 1172–1180, doi:10.3762/bjoc.15.114

• opening of 1 with Grignard reagents enables the synthesis of aryl and some alkyl-substituted BCPs and a subsequent cross-coupling reaction [5][18]. To provide bicyclo[1.1.1]pentylamine as a building block in large-scale syntheses, Bunker et al. developed a synthesis of hydrazine BCP via a manganese

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• . Nevertheless, most of the known multicomponent methods for the preparation of 2-oxindoles are based on the use of N-aryl amides as the main partner of the reagent pool. Wu et al. reacted N-(2-iodoaryl)acrylamides 113, DABCO·(SO2)2 (69, also known as DABSO) as a surrogate of sulfur dioxide and hydrazine 114 in

• a photoinduced, catalyst-free three-component reaction (Scheme 32) [110]. In this way, a variety of (2-oxoindolin-3-yl)methanesulfonohydrazides 115 with diverse substituents in the aromatic ring and hydrazine nitrogen, were prepared with moderate to good yields. This transformation may be explained

• hydrazine 114 and sulfur dioxide (Scheme 33). Rearrangement of the so-obtained intermediate 119, through radical 120, would provide oxindole 115. The same acrylamide 113 (R1 = H) has been recently used in another multicomponent synthesis along with CO (23) and benzodiazepine derivative 121 under palladium

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

• Angélica de Fátima S. Barreto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

• trifluoroethanol (TFE) were stirred at room temperature for 24 h to obtain acylhydrazino 1,5-disubstituted tetrazoles 14 in 30–100% yield. Attempts of this reaction without the use of catalyst provided the desired products in low yields. Subsequently, a hydrazinolysis reaction with hydrazine monohydrate led to the

• corresponding hydrazides 15, which were used in a second hydrazine-Ugi-azide reaction with various ketones, to obtain the acylhydrazino bis(1,5-disubstituted tetrazoles) 16 in yields ranging from 45–70%. Consecutive Ugi reactions for the synthesis of substituted α-aminomethyl tetrazoles have also been described

• hydantoinimide derivatives by consecutive Ugi reactions [17]. Synthesis of tetrazole-ketopiperazines by two consecutive Ugi reactions [19]. Synthesis of acylhydrazino bis(1,5-disubstituted tetrazoles) through two hydrazine-Ugi-azide reactions and a hydrazinolysis step [22]. Synthesis of substituted α

Efficient synthesis of pyrazolopyridines containing a chromane backbone through domino reaction

• Razieh Navari,
• Saeed Balalaie,
• Saber Mehrparvar,
• Fatemeh Darvish,
• Frank Rominger,
• Fatima Hamdan and
• Sattar Mirzaie

Beilstein J. Org. Chem. 2019, 15, 874–880, doi:10.3762/bjoc.15.85

• hydrogen in intermediate B, it is possible to form chromonyl-malononitrile conjugated system C and to eliminate the phenylhydrazine. Intermediate C is a highly potent Michael acceptor that may allow the addition of hydrazine to the nitrile group resulting in intermediate D that after elimination of water

• -resolution mass spectra and were recorded on Mass-ESI-POS(FT-ICR-Qe) spectrometer. General procedure for the synthesis of compounds 1a–g In a 25 mL flask containing 3 mL ethanol, 3-formylchromone derivatives (1 mmol) and hydrazine derivatives (1 mmol) were added and the mixture stirred for three hours at

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• /hexane 20%), resulting in 1.18 g (80%) of the cis-Gabriel amine. The free amine was obtained by the hydrazinolysis of the cis-Gabriel amine (0.40 mmol), in methanol (0.50 mL) with hydrazine hydrate (25%, 0.20 mL), stirred at room temperature for 24 h. To the mixture was added HCl until pH ≈ 2, forming a

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• reacted with the 2-chloroacetylacetone ester derivative 7 providing hydrazine 8 [66]. Upon reaction of the chloro-ester 8 with phenylenediamine (9) in the presence of triethylamine the quinoxaline moiety was formed [67]. Oxidation of the hydrazine derivative 10 using hydrogen peroxide under an oxygen

• substitution at a chloro-substituted purine (15a,b) or thienopyrimidine (15c), respectively, and subsequent oxidation of the hydrazine moiety afforded the corresponding azobenzene derivatives 16a–d [71]. Synthesis of azobenzene-extended thiopurine derivatives To further tune the photochromism and compare the