Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy

• Jiayue Fu,
• Bingbing Li,
• Zefang Zhou,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169

• trimethylsilylacetylene was performed to furnish aldehyde 3 [17][18] in 89% yield. A following nucleophilic addition reaction of aldehyde 3 by methylmagnesium bromide (MeMgBr) gave alcohol 4 in 99% yield, which was oxidized by pyridinium chlorochromate (PCC) leading to the formation of ketone compound and the

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• 27. Here, heteroaromatic, aromatic, and aliphatic aldehydes along with formaldehyde were taken into consideration providing the corresponding products in 33–76% yield (Scheme 6). Based on the plausible mechanism proposed by the authors, most likely the reaction began with the nucleophilic addition

• . Transition-metal-free three-component reactions, cycloaddition reaction methodology and nucleophilic addition reaction, mainly these three types of reaction methodologies can be found in the literature reports. The approaches were greener and the reaction conditions were milder or not harsh in most of the

Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)

• Yukiko Karuo,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1567–1574, doi:10.3762/bjoc.18.167

• 2n was 32% (Table 2, entry 13). In the case of aminophenol (3o), nucleophilic addition occurred predominantly at the phenoxide position and the product was obtained in moderate yield (Table 2, entry 14). An aryl iodide also participated in the reaction (Table 2, entry 15). We propose the reaction

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

• Pavel A. Topanov,
• Anna A. Maslivets,
• Maksim V. Dmitriev,
• Irina V. Mashevskaya,
• Yurii V. Shklyaev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

• formal [4 + 1] cycloaddition (Scheme 1). Results and Discussion FPDs are highly reactive compounds [25][26] containing an highly electrophilic enone fragment which facilitates the course of cycloaddition and nucleophilic addition reactions. In recent years, some types of cycloaddition reactions were

Ferrocenoyl-adenines: substituent effects on regioselective acylation

• Mateja Toma,
• Gabrijel Zubčić,
• Jasmina Lapić,
• Senka Djaković,
• Davor Šakić and
• Valerije Vrček

Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133

• no case, however, the ferrocenoylation reaction at the N6 position was observed in 1H NMR spectra. This is expected, as the nucleophilic addition pathway involving the quaternary ammonium intermediate is not viable. In all purine anions, according to the calculated Fukui functions f–, the N7 atom is

• for the reaction between N6-substituted adenine anions 1–5 and FcCOCl. In no case the tetrahedral intermediate, typical of a nucleophilic addition–elimination pathway, was located as a genuine minimum on the potential energy landscape. Instead, the structure with tetrahedral geometry corresponds to

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• activation [19]. Thereby, C3-triorganosilyl-substituted furfurals could be suitable platforms to develop a two-step modular approach to 3-substituted 2-furyl carbinols, entailing nucleophilic addition to the aldehyde function and oxygen-assisted electrophilic substitution of the C–Si bond (Scheme 1). Results

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• produce α-iodo ketone with the molecular I2 produced by anodic oxidation. Subsequently, the nucleophilic substitution between intermediate 4 and thiourea tautomer gives α-sulfur substituted ketone 5. Intermediate 5 undergoes intramolecular nucleophilic addition to the carbonyl group and followed by

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• : preussochromones E and F. Review 1. α-Ketoesters as key intermediates: (+)-Euphorikanin A In the final step of the synthesis of (+)-euphorikanin A (16), an ingenane-derived diterpenoid with a 5/6/7/3-fused tetracyclic carbon skeleton, Carreira et al. used an intramolecular nucleophilic addition of an alkenyl metal

• natural product preussochromone D (30) reported by Koert et al. [13]. The synthesis commenced with the efficient production of alcohol 26 from 5-hydroxy-4H-chromen-4-one (25, Scheme 5) [14]. The ketoester moiety was build up via oxidation and nucleophilic addition of methyl diazoacetate, yielding alcohol

• -ketoester 62, followed by nucleophilic addition of isopropenylmagnesium bromide to give α-hydroxyester 63 in excellent yield and diastereoselectivity. Eight additional steps gave the bicyclic compound 64 which was already known from previous camptothecin syntheses. Isoretronecanol The α-ketoester moiety can

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• antibacterial and antifungal activities [39][40][41]. The presence of an acyl group at the 4-position enables these heterocycles to be functionalized via nucleophilic addition reactions between the carbonyl group and nucleophiles like hydroxylamine and semicarbazide [42]. Herein, we report the synthesis of 4

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• base to catalyze the C–C bond formation via a Michael addition of active methylene groups [31]. Therefore, in the presence of TBAB, the bromide assisted with the deprotonation of the phenacylmalononitrile to give a carbanion intermediate A. Secondly, the nucleophilic addition of carbanion A to electron

• exist in cis-position. Sequentially, nucleophilic addition of the amino group of intermediate F to the C–C double bond connecting the two alkoxycarbonyl groups in molecule 3 resulted in the formation of intermediate G. At last, the base-catalyzed dehydration and elimination of hydrocyanide gave the

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• by two step hydrolysis gave the same product 223 in 28% yield. Phosphorus tribromide first reacted with more nucleophilic amide nitrogen atom to form dibromophosphanamine derivative 224 by loss of HBr. The more nucleophilic dibromophosphanamine derivative 224 further underwent a nucleophilic addition

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• this work. Firstly, the nucleophilic addition of tributylphosphine to the bis-chalcone gives the active zwitterionic species (A). Secondly, the Michael addition of the zwitterionic species (A) to isatylidene malononitrile at the C3-position of the oxindole scaffold results in adduct (B). Thirdly, the

• reaction, the nucleophilic addition of the zwitterion (A) to this compound takes place at the exocyclic position giving the adduct (E), which in turn proceeds with the intermediates (F) and (G) according to the above mentioned similar processes to give the spiro compound 5. The different addition direction

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• the nucleophilic addition and successive cyclization to happen. In addition, we further explored the scope of substrates with a trifluoromethyl group, a strong electron-withdrawing substituent, instead of methyl, an electron-donating group, in the 1,3-diketone starting materials (Table 2). The

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• )pyrroles [15]. The CsF-promoted nucleophilic addition of isocyanides to bromoacetylenes furnished the functionalized bromovinyl amides followed by Pd-catalyzed formation of 5-iminopyrrolone [16]. Sequential nucleophilic addition/intramolecular cyclization of amidine with bromoacetylenes led to imidazoles

Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates

• Ekta Gupta,
• Narendra Kumar Vaishanv,
• Sandeep Kumar,
• Raja Krishnan Purshottam,
• Ruchir Kant and
• Kishor Mohanan

Beilstein J. Org. Chem. 2022, 18, 217–224, doi:10.3762/bjoc.18.25

• thiourea moiety with the oxygen of the nitrosobenzene. The tertiary amine, present in the catalyst acts as a base in assisting the deprotonation of the highly acidic malonamate to generate the corresponding enolate. Subsequently, a face-selective nucleophilic addition of the enolate to nitroso selective

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• with reddish hues. The reaction with aniline forms the substitution product of the sulfonic group with a phenylamino group in a 90% yield. In his study, he proposed that the structure of the nucleophilic addition product was tautomer 19 (Scheme 1B). In search of a reagent that could form stable adducts

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• give amide 12 with a half-life (t1/2) of 6.4 h. The observation of N-formyl products can be rationalized with a bifurcating mechanism (Figure 5). Following photoactivation, H-atom abstraction and nucleophilic addition of water would produce the key intermediate B. Such hemi-aminal compounds would be

Me₃Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines

• Krishna M. S. Adusumalli,
• Lakshmi N. S. Konidena,
• Hima B. Gandham,
• Krishnaiah Kumari,
• Krishna R. Valluru,
• Satya K. R. Nidasanametla,
• Venkateswara R. Battula and
• Hari K. Namballa

Beilstein J. Org. Chem. 2021, 17, 2765–2772, doi:10.3762/bjoc.17.186

• achieved by treating 2-(2-oxo-2-phenylethyl)benzonitriles with amines in the presence of Me3Al. The reaction proceeds via a domino nucleophilic addition with subsequent intramolecular cyclisation. This method provides a wide variety of substituted 1-aminoisoquinolines with good functional group tolerance

• . Furthermore, the synthetic utility of this protocol was demonstrated in the successful synthesis of the antitumor agent CWJ-a-5 in gram scale. Keywords: 1-aminoisoquinolines; CWJ-a-5; intramolecular cyclisation; 2-(2-oxo-2-phenylethyl)benzonitriles; nucleophilic addition; Introduction Heterocyclic compounds

• suitably tailored benzonitriles 3 were cyclized in an intramolecular fashion by installing nuclophilic nitrogen onto the nitrile functionality would generate 1-aminoisoquinolines. Herein we describe our efforts on a Me3Al-mediated nucleophilic addition followed by an intramolecular cyclisation of 2-(2-oxo

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

• nucleophilic addition reactions using isatin-derived imines 50 as electrophiles was reported by Tan, Shi and co-workers in 2020. Enantioenriched 3,3'-bisindoles with a biologically essential chiral 3-aminooxindole unit can be readily prepared by these methods. CPA 9 utilizes hydrogen bonding to activate both

• accelerating imine formation (I-19), and under the catalysis of a chiral phosphoric acid, intramolecular nucleophilic addition occurs to form I-20, followed by oxidative dehydrogenation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). In the presence of 10 mol % chiral phosphoric acid CPA 7, the axially

• -yl)methanols 87 as electrophile and 2-naphthols 88 or phenols 90 as nucleophile (Scheme 29) [45]. The (3-alkynylindol-2-yl)methanol 87 is expected to convert to the allene-iminium intermediate I-24 by accepting a proton from CPA 14. Then, the CPA anion activates the nucleophilic addition between 2

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• photoexcitation the CuI acetylide A undergoes a SET process to form the CuII phenylacetylide species B and a superoxide radical anion. In parallel, under irradiation the homolytic S–S-bond cleavage in 2-aminothiophenol dimer 38 forms thiol radicals 40. The nucleophilic addition of the amino group in radical 40 to

• , the imine 60 transferred a single electron to the CuII ion, thereby providing intermediate II [CuI-N•+]. [CuI-N+•] was equal to CuI and N+• of the imine, which is activated for the nucleophilic addition. With the help of O2, CuI regenerates CuII to complete the catalytic cycle (Scheme 27). A series of

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• Petasis–Ferrier-type cyclization, and finally nucleophilic addition of mercuric enolate to iminium results in the formation of azaspiro structure. Conclusion In conclusion, this review summarizes Hg(II)-salt-mediated cyclization reactions either for direct synthesis of cyclized products or as a part of

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• these types of reactions. The first thiourea-catalyzed asymmetric intermolecular reaction with N-acyliminium chlorides was then also realized by the same group in 2009. Therein, nucleophilic addition of indoles 17 to the N-acyliminium chlorides was achieved with excellent enantiomeric excess (Scheme 4b

• , that Reissert dearomatizations of N-heteroarenes, especially of isoquinolines [36], and nucleophilic addition to 1-chloroisochromanes [38] have become benchmark reactions in the context of anion-binding catalysis. Besides reports of thiourea-catalyzed reactions with different nucleophiles [39][40], the

• have been provided by the group of Jacobsen in the nucleophilic addition of indoles 17 to pyranones 62 (Scheme 14a) [71], as well as in the enantioselective synthesis of α-allyl amino esters 67 by the reaction of α-chloro amino acid derivatives 65 with allyltin and allylsilane 66 nucleophiles [72

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• nucleophilic addition of the hydroxycoumarin. The procedure allowed obtaining products 34 with excellent yields and enantiomeric excesses (Scheme 11). Zhu et al. described the asymmetric Michael addition of substituted 4-hydroxycoumarins (1) to cyclic enones 36, using an in situ formed organocatalyst [44]. The

• half-thioesters 67 to coumarins 66 using a sulphonamide organocatalyst 69 was reported by Nakamura et al. [55]. The hydrogen bond between the secondary amine and the coumarin carboxyl provides a nucleophilic addition on the Re face, and therefore resulting in products 68 with R absolute configuration

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• corresponding triazole products in moderate yield (Scheme 8) [42]. The authors proposed a reaction mechanism in which the β-thioenaminone 18 tolerates deprotonation to afford anionic intermediate 21 through the tautomer 20 in the presence of a base. In the next step, the nucleophilic addition of 21 to the azide

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• after the nucleophilic addition as a stable bis-5,5-palladacycle (A), thereby preventing the β-hydride elimination step and allowing its further reaction with a proton to yield intermolecular hydroalkylation products (Scheme 5) [35]. In that work, the authors considerably expanded the scope of suitable