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Search for "guanidine" in Full Text gives 78 result(s) in Beilstein Journal of Organic Chemistry.
Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines
Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268
- with high diastereoselectivity (Scheme 5). In 2019, Shi and co-workers established a guanidine-catalyzed enantioselective (4 + 1) cyclization of benzofuran-derived azadienes 11 with 3-chlorooxindoles 18 [28]. This work provides a useful strategy for the synthesis of chiral spirooxindole derivatives 19
- -chlorooxindole 18 has an essential role in the reaction. The proposed reaction pathway for the enantioselective (4 + 1) cyclization is illustrated in Scheme 6. Initially, chiral guanidine VI, acts as a Brønsted base deprotonating the enolic form of 3-chlorooxindole whilst simultaneously activating the benzofuran
- -derived azadiene by H-bonding. This dual activation promotes a stereoselective addition of 3-chlorooxindole to the azadiene leading to intermediate A. The latter is also activated by the chiral guanidine and undergoes an intramolecular nucleophilic substitution which delivers the product 19b with the
Hypervalent iodine-mediated intramolecular alkene halocyclisation
Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258
- . The authors proposed two possible mechanisms for the reaction (Scheme 24). Firstly, a chloronium ion is generated by HVI and LiCl followed by intramolecular nucleophilic attack by nitrogen to form the heterocycle. Secondly, oxidation of the unsaturated guanidine forms an intermediate aziridinium A
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- securing the enantioselectivity of the reaction by locking the catalyst in the more active and enantioselective Z-configuration (Figure 2). Further, the authors found that H-bond donors featuring urea, thiourea, and guanidine motifs were either inactive or provided racemic mixtures. Among 3,5-dichloro
Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines
Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198
- nitroalkenes or guanidine-mediated addition of bisthiomalonates to maleimides, cyclic enones, and acyclic 1,4-dicarbonylbutenes, albeit at low temperatures and with relatively long reaction times, further limited to a narrow scope of thioesters (Scheme 1) [31]. Recently, we described a cinchona-squaramide
- guanidine motif in AA-3 compared to simple AA-1. Alterations in the thiol structure within thiomalonates significantly impact their stability and reactivity, thereby influencing both reaction efficiency and stereochemical outcome, as demonstrated in the case of catalysis employing bifunctional hydrogen bond
Synthesis of ether lipids: natural compounds and analogues
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
Organic thermally activated delayed fluorescence material with strained benzoguanidine donor
Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95
- : guanidine; organic; photoluminescence; TADF; yellow; Introduction Thermally activated delayed fluorescence (TADF) is a photoluminescence mechanism where excitons undergo thermally-assisted reverse-intersystem crossing from an excited triplet state to a higher-lying in energy singlet state to emit delayed
Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update
Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72
- expansion was carried out by employing 2-naphthol and 4-hydroxyindole (Scheme 34) [64]. Application in total synthesis In 2018, a guanidine bisthiourea-catalyzed highly enantioselective aza-Friedel–Crafts reaction was applied as a central step in the total synthesis of (+)-gracilamine. The reaction was
Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1
Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69
- ], the cyclic guanidine alkaloid massinidine [17], and the siderophore massiliachelin [18]. An antiSMASH analysis [19] of the genome of Massilia sp. NR 4-1 revealed the presence of additional biosynthetic gene clusters, including another putative metallophore gene cluster (ACZ75_RS05545–ACZ75_RS06020
Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment
Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58
- guanidine C. Finally, the intramolecular cyclization of the guanidine moiety and the carbonyl group leads to the target pyrimidine 9. After the general synthetic method for pyrimidines containing the allomaltol fragment had been established, the photochemical behavior of the obtained compounds 9 was
Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme
Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40
- fluorescence response. Compounds that consisted of pyrrole-guanidine attached to larger aryl moieties (pyrene and phenanthridine) bind to the human DPP III enzyme [17]. Pyrene–cyanine conjugates connected with a rigid triazole-peptide linker were designed and synthesized in our group and showed a strong pyrene
Mechanochemical solid state synthesis of copper(I)/NHC complexes with K3PO4
Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34
- sophisticated copper(I)/N-heterocyclic carbene complex bearing a guanidine moiety. In this way, the present approach circumvents commonly employed silver(I) complexes which are associated with significant and undesired waste formation and the excessive use of solvents. The resulting bifunctional catalyst has
- an ester reduction with H2 as terminal reducing agent utilizing bifunctional copper(I)/NHC complex 5 bearing a guanidine moiety as additional catalytic unit [48]. This catalyst acts by employing the copper(I)/NHC complex for H2 activation on the one hand and by using the guanidine subunit for
- hypothesize that in this CO2 adduct, the guanidine moiety is unavailable to perform its assisting part in catalysis through hydrogen-bonding interaction [48]. As additional evidence to support the formation of the CO2 adduct of 5, we can show that bubbling of CO2 through a solution of 5 leads to catalytically
Synthesis and reactivity of azole-based iodazinium salts
Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27
- underwent undesired ring openings. Treating 12 with BocNH2 resulted in the formation of protected guanidine 15 in 80% yield (Scheme 2c), which would not be possible to obtain via an oxidative cyclization of the corresponding iodine(I) species due to a carbamate cleavage with acid. The other dicationic salts
- underwent ring openings in this reaction. This reactivity demonstrates the highly stabilizing effect of N-heterocycles on hypervalent iodine species. Furthermore, the formed 2-aminobenzimidazoles reveal new access to potential bioactive compounds [46][47]. Even the formation of the free guanidine 16 via
Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives
Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24
- endocyclic nitrogen with a benzyl or alkyl unit functionalized either with non-polar hydrocarbons or a polar amine, amidine and guanidine group. The ensuing assay with the model GMIIb enzyme (fruit fly Golgi α-mannosidase II) revealed that N-substitution improved both potency and selectivity, achieving
- (AMAN-2) (GH38 family, E.C.3.2.1.114) was included in the biochemical assay as its active site is more similar to human GMII than that of GMIIb. The resulting biochemical evaluation revealed that imino-ᴅ-lyxitols with N-substituents possessing a polar basic functional group (amidine or guanidine) were 6
New efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines through a Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution sequence
Beilstein J. Org. Chem. 2022, 18, 286–292, doi:10.3762/bjoc.18.32
- . Compound 4a was then allowed to react with triphenylphosphine in CH2Cl2 at room temperature for 2 h to produce the iminophosphorane 5a by Staudinger reaction. Aza-Wittig reaction of 5a with phenyl isocyanate generated carbodiimide 6a, which was then treated with diethylamine to form the guanidine
- intermediate 7a. In the presence of K2CO3 in CH3CN at refluxing temperature, the 3,4-dihydroquinazoline 8a was finally obtained in 84% yield (Table 1, entry 1, the overall yield is 73%) by intramolecular nucleophilic substitution. The reaction conditions for the transformation of guanidine intermediate 7a into
Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides
Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125
- between the modified nucleobase and the corresponding guanidine, which resulted in an increase in Tm of 16 °C, i.e., in the same range as obtained with the original G-clamp (Table 3A) [59]. Generally, conversions of nucleoside phosphoramidite synthons have been explored only rarely. However, the
- NaCl) [68]. It has been demonstrated that C-2 modified guanidine analogues containing nor-spermidine (30) and the shorter diethylenetriamine (29) (Table 3D) could be synthesized via the C2-fluoro modified monomer. This resulted in ONs with slightly higher Tm (approximately 3 °C for 29 and 30) when
- effects. The best stabilization was obtained for the 2-(aminoethyl)guanidine monomer 45 and tris(2-aminoethyl)amine (monomer 44) variants [80]. Another chemical group utilized for the 2’-modification is 2’-O-carbamoyl [85][86][87]. However, it has proven difficult to stabilize the duplex formed between
Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications
Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116
- stability of duplexes [79][80]. Ly and co-workers showed that γ-modified PNA derived from ʟ-arginine (γ-GPNA, Figure 5) were preorganized into a right-handed helix, which improved their binding to complementary DNA and RNA while retaining sequence selectivity [81]. As expected, the guanidine modifications
- using only Watson–Crick base pairing to recognize the target [89]. As will be discussed later in this review, PNAs having guanidine (γ-GPNA) and miniPEG γ-modifications are currently among the most promising PNA derivatives explored in medicinal chemistry and preclinical studies. Anionic PNA: Anionic
- cationic RNA binding compounds, perhaps, because the protonation event is coupled with the Hoogsteen hydrogen bond formation. As a result, the partially protonated M strengthens the triple helix without compromising the sequence specificity of recognition [28][30][31]. As discussed above, guanidine groups
Synthetic accesses to biguanide compounds
Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82
- : amidine; biguanide; guanidine chemistry; metformin derivatives; polynitrogen ligands; synthetic methodology; Introduction Biguanide – or amidinoguanidine – is a chemical compound derived from guanidine in which two guanidine molecules are linked through a common nitrogen atom. Since its first synthesis
- Biguanides were named by their discoverer B. Rahtke, as he believed this entity could be obtained through the condensation of two guanidine units via evolution of ammonia. In 1972, this class of compounds was renamed by chemical abstracts as imidodicarbonimidic diamide. However, for sake of clarity, the term
- “biguanide” will be used in this review. Despite being related to guanidine, biguanide is a totally distinct and unique chemical function with its own properties and reactivity. It is a small chemical group comprising five heteroatoms, five potential H-bonds accepting sites, at least five H-bonds donating
Synthetic reactions driven by electron-donor–acceptor (EDA) complexes
Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67
- functional-group tolerance are provided by this approach, yielding multiple indole analogues with biological activity. In 2017, Liang and Bi [56] reported a visible-light-induced three-component cyclization of ethyl acetoacetate (23), perfluoroalkyl iodides 24, and guanidine hydrochloride (25) via a halogen
Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases
Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54
- synthesis of 2'-amino-LNA (Figure 1) functionalized with a peptide or sugar at the N2'-position, with the aim of modulating the physicochemical properties and specific organ distributions of the therapeutic oligonucleotides [13][14]. A more favorable example is the covalent attachment of a guanidine moiety
- , which is a common approach to partially neutralize the polyanionic property of oligonucleotides [15][16][17][18]. In our previous study, a guanidine-bridged nucleic acid (GuNA[H]; Figure 1) bearing a thymine (T) nucleobase was synthesized as a novel artificial nucleic acid for antisense applications [19
- ]. The modification of oligonucleotides with GuNA[H]-T improved the nuclease resistance, cell membrane permeability, and binding affinity toward complementary single-stranded DNAs (ssDNAs) and RNAs (ssRNAs). We also synthesized and evaluated a GuNA[H]-T analog bearing a methyl group in the guanidine
Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds
Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14
- a variety of pyrimidine derivatives, 6, using amidines including guanidine [34]. First of all, various bases were employed for the reaction of the model substrate 2a. During initial testing, guanidine hydrochloride at 25 °C for 4 h in acetonitrile (Table 5, entries 1–7) as well as sodium carbonate
- as shown in Table 5, entry 14, which included heating the reaction mixture at 80 °C for 8 h in MeCN, furnishing the desired pyrimidine 6aa in 60% isolated yield. Then, four types of ynones, 2a–d, were reacted with formamidine and acetamidine as well as guanidine under the optimized conditions
- outlined above, the results of which are summarized in Table 6. When the reactions were performed with acetamidine and guanidine, a good to high yield was recorded, while only a lower yield was obtained by the application of formamidine acetate, for which the reaction was not further elucidated at this
Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group
Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162
- methoxide in guanidine hydrochloride buffer solution (pH ≈ 9) to remove the O-3,4,6-acetyl groups [14]. Because the deacetylation reaction was later neutralized with cation exchange resin, extra washing with saturated NaHCO3 during reaction work-up seemed necessary to avoid cleavage of the TBS ether in
- monoacylated glucosamine building blocks. Conditions: (a) NaHCO3, TrocCl, H2O, 0 °C, 94% ; (b) Ac2O, pyridine, rt, 96%; (c) N2H4, AcOH, DMF, rt, 89%; (d) TBSCl, imidazole, DMF, rt, 93%; (e) guanidine hydrochloride buffer, rt; (f) NapC(OMe)2, camphorsulfonic acid, CH3CN, rt, 68% (2 steps); (g) acid 7, EDC·HCl
Copper catalysis with redox-active ligands
Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77
- use of copper(I) complexes bearing redox-active guanidine ligands 12 for catalytic aerobic homo- and cross-coupling of phenols with dioxygen as oxidation source (Scheme 9). This strategy allowed access to nonsymmetrical biphenols and the best results were obtained with dinuclear complex 13
- trifluoromethylation of heteroaromatics with redox-active iminosemiquinone ligands. Reversal of helical chirality upon redox stimuli and enantioselective Michael addition with a redox-reconfigurable copper catalyst. Interaction of guanidine-copper catalyst with oxygen and representative coupling products. a4 mol
A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions
Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52
Architecture and synthesis of P,N-heterocyclic phosphine ligands
Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35
- with aminosilanes which produces trimethylchlorosilane as a byproduct which can be distilled off easily [102]. Bicyclic guanidine frameworks present an opportunity to form inflexible ligands that are inclined to exhibit a κ2-P,N-bonding mode in metal complexes. Dyer et al. [103] prepared cycloguanidine
A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones
Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287
- from lactone to 20% (Scheme 2). Due to the interest in the potential preparation of pyrimidines from β-ketonitriles and guanidine [18], we wanted to test the general applicability of this method for access to a variety of alkyl and aryl-substituted β-ketonitriles (as summarized in Table 1). When we
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