Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• selectively produced by using differently substituted 3-methyleneoxindoles (reaction 4 in Scheme 1). Herein, we wish to report these interesting results. Results and Discussion At first, 3-isatyl-1,4-dicarbonyl compound 1 was prepared by DBU-catalyzed Michael addition reaction of dimedone and ethyl 2-(2

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• hydrolysis of 2,5-DMTHF (2), which provide intermediate C after the removal of methanol in the presence of CuCl2. In the next steps, nucleophilic addition reaction of amines 34 with intermediate C, dehydration, and intramolecular aromatization affords N-substituted pyrroles 35. In 2018, Patil and Kumar [70

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• , intermediate 13 was transformed to (±)-6,7-secoagroclavine in enantiopure form, as reported previously by the Bisai group in 2018 [115]. All the spectroscopic data of 13 were in agreement with those reported in the literature, confirming that the radical addition reaction provided the trans amino group due to

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• (NaBEt3H) and aided by organoboranes (Scheme 12c). The proposed mechanism (Scheme 12d) involves the formation of the organoborate intermediate 60 from alkene 58 in the presence of the NaBEt3H catalyst and the organoborane. Next, the organoborane-activated pyridine species 61 undergoes an addition reaction

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• of 93:7 using ligand L25. Recently, Chegondi and co-workers have demonstrated an enantioselective Cu-catalyzed tandem borylation/Michael addition reaction of aryl enones 167 and 170 to cyclohexadienones in an intramolecular fashion (Scheme 43A) [84]. The 1,4-conjugate borylation is followed by a

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• (RCysNi)L7 formed in the Michael addition reaction was confirmed using the NOESY spectrum. It is illustrated in Figure 1 for (oBrCysNi)L7 complex as the representative example. A correlation between the signal of the H-2 proton at the α-amino acid stereocenter with the signal of the ortho-protons of the

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• addition reaction involved. The low reactivity of intermolecular RC reactions can be improved by incorporating the nucleophilic functionality within a molecule like I (Scheme 1). This nucleophilic functionality present within the enone system first undergoes an intramolecular conjugate addition and is

• involvement of one intramolecular and one intermolecular conjugate addition reaction leads to notable high acceleration in RC reactions. Based on the accelerated intermolecular Rauhut–Currier reaction reported in the literature [7][8][9] and our interest in the synthesis of dimeric complex natural products

• to the dihydroxy RC product (±)-4. Synthesis of dihydroxy product (±)-4 was carried out at gram-scale utilizing the key accelerated RC dimerization. In order to synthesize (±)-incarvilleatone (1) first, we needed to perform an oxa-Michael addition reaction. For this, we screened various bases [11][12

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

• reaction of Meldrum’s acid (26) and aldehyde 27 resulting in the formation of the electron-deficient enone 30, which then participated in a Michael-type addition reaction with 1,3-dipolar 2-unsubstituted imidazole N-oxide 28 to provide the intermediate 31. In the last step, the final product 29 was

• . 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

• 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

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

• Mana Kitano,
• Tsuyoshi Saitoh,
• Shigeru Nishiyama,
• Yasuaki Einaga and
• Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

• 10.3762/bjoc.18.119 Abstract A straightforward electro-conversion of cumene into acetophenone has been reported using boron-doped diamond (BDD) electrodes. This particular conversion is driven by the addition reaction of a cathodically generated hydroperoxide anion to an anodically generated cumyl cation

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• , it was observed that the MBH reaction of 6b with acrylonitrile A resulted in the formation of product 8bA which evidenced that 6b underwent Morita–Baylis–Hillman reaction at the electrophilic carbonyl center as well as Michael addition reaction at the nucleophilic nitrogen center (N-9). Similar

• . This difference in the fluorescence intensity values of compound 7 and 8 may be attributed to the addition of a substituent at N-9 position of the β-carboline ring after Michael addition reaction (CH2CH2CN or CH2CH2CO2Me). Conclusion In conclusion, we have successfully explored 3-formyl-1-aryl-9H

• -pyrido[3,4-b]indole derivatives for the C-3 functionalization by application of the MBH reaction to generate C-3-substituted β-carboline MBH adducts. It was revealed from spectroscopic analysis that few derivatives underwent MBH reaction as well as Michael addition reaction to form type 8 compounds

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• ]. Notably, the dissipative conditions were realized by addition of a fuel acid [113][114] that surprisingly ignited a base-catalyzed Knoevenagel addition reaction (Figure 25). As DABCO is a stronger binding ligand (log β = 7.20) [115] towards zinc porphyrin (ZnPor) than pyridine (log K = 4.45) [90] the

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• ketoacids [39]. In the present study, in continuation of our interest in the synthesis of functionalized DHPMs [27], we utilized β,γ-unsaturated ketoesters and subjected them to the melt conditions to achieve the synthesis of 5-unsubstituted DHPMs. We envisaged that the simple Michael addition reaction of

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• mixture of different products will form through various pathways [50][51][52][53]. By applying the cage host A, the authors realized a highly site-selective radical addition reaction of o-quinone 10 and substituted toluene 11, giving rise to the unusual 1,4-adduct 15 (Figure 3) [54]. Specifically, upon

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

• as a pro-nucleophile in an enantioselective addition reaction. The mild reaction conditions allow the use of various functionalized malonamates. Given the importance of highly functionalized α-amino acid derivatives, the present strategy could be useful in generating a wide range of α-oxyamino

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• under the action of catalyst C4. Simultaneously, deprotonated 1a attacks the double bond of 2a from the Si face via intermediate A, resulting in a Michael addition reaction. Then the electron-deficient isothiocyanate moiety is attacked by newly generated α-carbon center from barbiturate-based olefins 2a

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• reductive strategy through nitrogen loss of sulfonyl hydrazones [13][14]. In addition, a sulfa-1,6-conjugated addition reaction [15][16][17] has also been developed for this purpose. Most of the reported methods are affected by long reaction times and the need for expensive metal catalysts or reagents

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

• asymmetric addition reaction of racemic naphthylindole 42 with azodicarboxylate 43 under chiral phosphoric acid catalysis. In the presence of CPA 2, 42 and 43 reacted and underwent dynamic kinetic resolution to afford naphthylindoles 44 with axial chirality in moderate to good yields (50–98%) and high

• enantioselectivity (91:9 to 98:2 er, Scheme 15) [65]. In addition, the authors also succeeded in preparing naphthylindoles 46, which exhibit both axial and central chirality, through the addition reaction of racemic naphthylindoles 42 and o-hydroxybenzyl alcohols 45 using chiral phosphoric acid CPA 13. This reaction

• also achieved the first catalytic asymmetric construction of axially chiral 3,3’-bisindole scaffolds 49 bearing both axial and central chirality by employing the CPA-14-catalyzed asymmetric addition reaction of 2-substituted 3,3’-bisindoles 47 to isatin-derived 3-indolylmethanols 48. The isatin-derived

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

• Akhil K. Dubey and
• Raghunath Chowdhury

Beilstein J. Org. Chem. 2021, 17, 2642–2649, doi:10.3762/bjoc.17.177

• organosilanes [29][37][38], we present herein an organocatalyzed conjugate addition reaction of nitromethane to β-silyl enones to afford chiral β-silyl nitroalkanes (Scheme 1). Notably, the developed method was not only carried out under solvent-free conditions at room temperature but was found to be tolerant

• the best of our knowledge, organocatalyzed or metal-catalyzed enantioselective conjugate additions of nitroalkanes to β-silyl enones are not yet known. Results and Discussion The optimization study began with the conjugate addition reaction between β-TMS enone 1a and nitromethane (2) as the model

• limitations of this enantioselective conjugate addition reaction. Under the optimized reaction conditions, the conjugate addition reaction of nitromethane (2) to a variety of β-silylenones 1 was carried out and the results are summarized in Scheme 2. β-Silylenones bearing electron-donating, electron

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• reactions [34][35]. In 2015, Zhao et al. synthesized spiro[pyrrolidine-3,3'-oxindoles] 29 in single step by asymmetric cascade aza-Michael/Michael addition reaction between 4-tosylaminobut-2-enoates 27 and 3-ylideneoxindoles 26 catalyzed by a chiral bifunctional tertiary amine, squaramide (cat. 28) which

• afforded the corresponding adducts in good yields ranging from 72–99% with excellent diastereoselectivity (up to >99:1 dr) and enantioselectivity (>99% ee) (Table 6) [36]. In another report, Yang et al. accomplished a highly asymmetric cascade aza-Michael/Michael addition reaction for the synthesis of

• acids have been shown to catalyze the reactions via single or double hydrogen bonding [57][58]. Saito et al. accomplished the chiral phosphoric acid-catalyzed intramolecular aza-Michael addition reaction of N-unprotected 2-aminophenyl vinyl ketones 90 to obtain chiral 2-substituted 2,3-dihydro-4

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• dibromopyrroles 38, respectively. Subsequently, Punniyamurthy and co-workers also described the copper-catalyzed cascade cyclization of 2-nitro-1,3-enynes 34 to tetrasubstituted pyrroles 39 (Scheme 14) [58]. Through screening the conditions, the Cu(OTf)2-promoted (5 mol %) annulation addition reaction of 2-nitro

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• ], rhodium-mediated alkyne [2 + 2 + 2] cycloaddition reactions [3], and the palladium-catalysed aerobic domino Suzuki coupling/Michael addition reaction [4]. The most attractive and common strategies to phenanthridines rely on intramolecular cyclizations of various ortho-functionalized biaryl precursors

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

• process displayed good regioselectivity (Scheme 10) [23]. The authors proposed that the reaction may proceed through the mechanism illustrated in Scheme 11. Initially, EDAM 24 is treated with an azide source and subsequently, the intermediate 26 is formed through 1,2-addition reaction. The intermediate 26