Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• , automation in ASFRs reduces the need for constant human oversight, lowering operational costs and minimizing the risk of human errors. A schematic representation of ASFR is provided in Figure 5a. A self-optimizing microreactor system has been devised specifically for closed-loop optimization of the Heck

• reaction, employing a "black-box" optimization strategy directed by Nelder–Mead simplex method algorithm [57]. In-line HPLC analysis was performed to determine the product yield in real time and give feedback to the control system to direct the input conditions to achieve the optimum product yield in 19

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• ) [101][102]. Our group attempted to use (E/Z)-1,2-difluoroethylene in a Heck reaction [78]. The experiments were performed using 4-iodotoluene or methyl 4-iodobenzoate in DMF, Pd(OAc)2 as a catalyst, and Et3N as a base (Scheme 25). The reactions were carried out in a stainless steel autoclave at 120 °C

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• ). The proposed mechanism, shown in Scheme 34, suggested that the process proceeded through a Pd(0) catalysis proceeding through first an intramolecular Heck reaction, followed by CO insertion, N-cyclization (anilines) or O-cyclization (phenols) and final reductive elimination. Carbonylative

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• and Heck cyclization reactions. The integration of the multicomponent and post-condensation reactions in one-pot maximizes the pot-, atom-, and step-economy (PASE). Keywords: Heck reaction; one-pot; tetrahydroisoquinoline; tetrazolo-pyrazino[2,1-a]isoquinolin-6(5H)-ones; tetrazole; Ugi-azide reaction

• used as the isocyanide source, the Ugi-azide reaction gives rise to ring-fused tetrazolo[1,5-a]pyrazin-6(5H)-one adducts 5. The subsequent Pd-catalyzed intramolecular Heck reaction of compounds 5 or 7 then affords 1,2,3,4-tetrohydroisoquinolines 6 and 8, respectively. Results and Discussion Following

• effort was then focused on the optimization of the intramolecular Heck reaction of 5a for making 1,2,3,4-tetrahydroisoquinoline 6a. A systematic evaluation of different catalysts and ligands, solvents, bases, as well as reaction temperatures and times was conducted (Table 1). The Heck reaction of 5a was

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• crossover process [47][48][49][50]. However, activated alkyl halides are not suitable for these carboamination reactions due to the direct nucleophilic substitution of activated alkyl halides with nucleophilic reagents under the necessary alkaline conditions [51]. Recently, a Pd-catalyzed alkyl Heck

• reaction of diazo compounds mediated by visible light has been reported by the group of Gevorgyan, which achieves the monofunctionalization of alkenes [52]. Inspired by these collective studies, we considered diazo compounds could be a competent activated alkyl halide equivalent to overcome the synthetic

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• -bromo-4-iodotoluene with 1,1-diphenylethylene yields the desired 9-arylphenanthrene 28 via a Heck reaction followed by intramolecular C–H arylation (Scheme 6). However, partial conversion of the starting material was observed. The use of 3 equiv KOPiv and 3 equiv Cs2CO3 as a base mixture increased the

• -arylphenanthrenes 28–30 via Heck reaction followed by intramolecular C–H bond arylation The reaction of the 1,1-diphenylethylene (0.180 g, 1 mmol), 1,2-dihalobenzene (1.5 mmol), KOPiv (0.420 g, 3 mmol) and Cs2CO3 (0.978 g, 3 mmol) in the presence of PdCl(C3H5)(dppb) (30.5 mg, 0.05 mmol) at 150 °C during 16 h in DMA

• -dihalobenzenes. Pd-catalyzed Heck reaction followed by direct arylation of 1,1-diphenylethylene with 1,2-dihalobenzenes. Influence of the conditions on the Pd-catalyzed reaction of 1,8-dibromonaphthalene with 1,2,3,4-tetrafluorobenzene.a Supporting Information Supporting Information File 43: Characterization

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• Pd-catalyzed Heck reaction to give products 26 in 65–78% yields (Scheme 16) [75]. The pyrrolo[2,1-a]isoquinoline core installed by this route can be found in some natural products and synthetic compounds with antitumor, antibacterial, antiviral, antioxidizing, and other biological activities (Figure

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• accessed from tropone (via its η4-diene complex with Fe(CO)3) in a short sequence of steps: 1) nucleophilic amine addition and subsequent Boc-protection, 2) photochemical demetallation of the iron complex, and 3) an intramolecular Heck reaction. Minor modifications to the protocol enabled access to the

• related 2-azabicyclo[4.4.1]undecane system, albeit in lower yield. Keywords: alkaloids; azabicycles; Heck reaction; iron complex; tropone; Introduction Azapolycycles are embedded within numerous biologically active alkaloids [1] and pharmaceuticals [2]. As such, novel approaches to the synthesis of

• ervitsine [10][11] (Figure 1). We reasoned that, with an appropriately functionalized amine side chain and properly disposed unsaturation on the seven-membered ring, an intramolecular Heck reaction could give rise to skeleton 4 in just a few steps from tricarbonyl(tropone)iron (Scheme 1). Herein, we report

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• . Among these, Heck reaction conditions allowed for the coupling of aryl acrylates 50 to aryl halides 48 and 49, followed by intramolecular Pd-catalysed amination or etherification to give C-10 carboxylates of dibenzo[b,f]azepine 55 and dibenz[b,f]oxepine 54 in good yield (Scheme 11). However, no ring

• -substituted derivatives were reported. The authors used alpha-substituted acrylates to reduce the effect of poor endo/exo regioselectivity in the intramolecular Heck reaction (cf. Scheme 19). Božinović et al. [52] reported the synthesis of symmetrical 5H-dipyridoazepines 60a and unsymmetrical 5H

• final Mizoroki–Heck reaction will be discussed in the following section. The Buchwald group [59] reported a ligand-controlled divergent synthesis involving intramolecular cyclisation, allowing for the formation of several heterocycles, including dibenzo[b,f]azepines 89, in two steps. Screening of

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• Mizoroki–Heck reaction: construction of the [5-8] bicyclic ring system of brachialactone A study of the versatility of the Mizoroki–Heck reaction in an intramolecular version was recently described by Nishikawa to elaborate the eight-membered ring of brachialactone (7) (fusicoccane series) from an advanced

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• and the aromatic moieties present in these natural products and provided the common synthetic intermediate 70 (Scheme 6). The diverse tetracycles were accessed either via an intramolecular radical cyclization of the reduced congener 73 or through a Heck reaction of intermediate 71. Reaction of 73 with

• conditions of the Heck reaction to common scaffold 70 proved unsuccessful. Screening of several reaction conditions on different analogues led to the conclusion that reduction of the C8-carbonyl side and acetal deprotection to 71 are essential in order to create the 6/6/5/6-carbocycle in the presence of Pd2

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

• transformations. For example, bromoacetylenes were demonstrated to add imidazoles, imidazolines [12], and benzimidazoles [13][14] to give vinyl bromides. Sulfonamides reacted with bromoacetylenes to deliver N-bromovinyl-p-toluenesulfonamides that under Heck reaction conditions afforded N-(p-toluenesulfonyl

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• -phenylhydrazine in acetic acid that delivers methyl 2-(1-benzyl-3-(2-nitrophenyl)-1H-indol-2-yl)acetate in 55% yield. Keywords: anticancer; Fischer indole synthesis; Heck reaction; heterocyclic compounds; indolobenzazepines; latonduines; paullones; Introduction Indolobenzazepines are fused heterocyclic

• -oxobutanoate (Scheme 1). To construct scaffold C by route (a) we first tried to synthesize 3-(2-nitrophenyl)indole by Heck reaction of indole and o-iodo-nitrobenzene [25]. However, in this case we obtained an isomeric mixture of 3- and 2-(2-nitrophenyl)indole in a 3:1 molar ratio, quite difficult to separate

• by column chromatography. Protection of the indole nitrogen by an ethoxymethyl group (Scheme 2) and the use of protected indole 4 in the subsequent Heck reaction resulted in a significantly lower conversion of 22% vs 64% for the unprotected indole. However, the protection of the indole nitrogen atom

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• way for the synthesis of compounds 2. These compounds can be alternatively obtained by a Pd-catalyzed Heck reaction of 3-arylpropenenitriles with iodoarenes [23] or by a Cu-catalyzed hydroarylation of 3-arylpropynenitriles with arylboronic acid [24][25]. There is one example of use of dicyanoacetylene

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• be a challenging endeavor. As conventional methods, e.g., the Heck reaction are incompatible with quinones [15], a large subset of research recently focused on radical-based CH-arylation reactions. In 2011, Baran published a seminal paper that relied on using a AgNO3/K2S2O8 induced homolytic

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• was chosen DMF, although the use of polar aprotic solvents usually leads to products of the oxidative Heck reaction. The authors noticed a significant reduction of Pd(II) to Pd(0) (by secondary processes such as oxidative homocoupling or oxidation of boronic acid to the corresponding phenol). The Pd(0

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• catalysts in various organic reactions [1] such as the Ullmann coupling, Suzuki coupling, Suzuki–Miyaura coupling, and the Heck reaction. Aside from being useful synthetic agents, biguanides gained particular interest from the perspective of medicinal chemistry. For the first time, the biological activity

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions

• Xiaoming Ma,
• Suzhi Meng,
• Xiaofeng Zhang,
• Qiang Zhang,
• Shenghu Yan,
• Yue Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106

• ]isoquinolines. The multicomponent reaction was combined with one-pot reactions to make a synthetic method with good pot, atom and step economy. MeCN was used as a preferable green solvent for the reactions. Keywords: [3 + 2] cycloaddition; Heck reaction; hexahydropyrrolo[2,1-a]isoquinoline; one-pot reactions

• evaporating unreacted 3-bromopropene (7) from the reaction mixture, crude product 8a was used for developing the intramolecular Heck reaction by screening Pd(II) catalysts, ligands, bases, additives, solvents, temperatures and reaction time (Table 1). The initial intramolecular Heck reactions were carried out

• , entry 3). Other attempts to improve the Heck reaction using different ligands, such as (P(o-tol)3, PCy3 and dppm, were not successful (Table 1, entries 4–6). The reaction at 105 °C in MeCN gave 9a in 78% yield (Table 1, entry 7), while at 120 °C in DMF gave 9a in 77% yield (Table 1, entry 11). Reducing

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

• the key fundamental principles of boron and palladium speciation and the role of the base in the Suzuki–Miyaura reaction. For researchers developing safer solvents, the Mizoroki–Heck reaction is a more suitable cross-coupling methodology to demonstrate solvent performance [28]. The reaction kinetics

• Mizoroki–Heck reaction and hence there is also a motivation to investigate safer alternative solvents that the Suzuki–Miyaura reaction lacks. If researchers are still compelled to study the utility of solvents in the Suzuki–Miyaura reaction, I encourage future studies to be directed at challenging

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• Pd-catalysed Fujiwara–Moritani or oxidative dehydrogenative Heck reaction via dual C–H activation [21][22][23][24]. One of the early examples of this reaction, reported by Gaunt and co-workers, involved the regioselective, solvent-controlled C3 alkenylation of indoles with alkenes containing electron

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• ]pyridine ring has been synthesized via the microwave-assisted Mizoroki–Heck reaction. The efficient modification of the imidazo[1,2-a]pyridine ring has been achieved as late-stage functionalization, enabling and accelerating the generation of a library of compounds from a common precursor. Keywords: α

• -phosphonoacrylates; α-phosphonopropionates; imidazo[1,2-a]pyridine; microwave-assisted reaction; Mizoroki–Heck reaction; Introduction In the last few decades, the Mizoroki–Heck reaction has become one of the main tools in organic synthesis. Its use for the functionalization of a wide range of compounds cannot be

• confirmed by the presence in a number of pharmaceuticals [2][3]. The imidazo[1,2-a]pyridine-ring modification via Pd-catalyzed reactions is broadly reported in the literature [3], however, such functionalizations for more complex molecules are not very common. On the other hand, the Mizoroki–Heck reaction

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

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

• and 2e were obtained in moderate yield using 3a as the aryl halide in the Heck reaction. The use of 3b in the Heck reaction resulted in a substantial improvement of yield in the synthesis of 2g but not for 2c. Interchanging the roles by using 5-vinylnicotinamide (5a) or methyl 5-vinylnicotinate (5b