One-step route to tricyclic fused 1,2,3,4-tetrahydroisoquinoline systems via the Castagnoli–Cushman protocol

• Aleksandar Pashev,
• Nikola Burdzhiev and
• Elena Stanoeva

Beilstein J. Org. Chem. 2020, 16, 1456–1464, doi:10.3762/bjoc.16.121

• spectroscopy. The spectra showed cross peaks between the protons from the cis-oriented alkyl-C-11b and H-1, which unequivocally proved the trans relative configuration of the substituents at C-1 and C-11b (Figure 4). 1-Alkyl-3,4-dihydroisoquinolines have been reported to react as C-nucleophiles or 1,3-C,N

• -ambident nucleophiles with electrophilic species [47][48][49][50]. Thus the formation of compounds 25–27 could be rationalized as including an initial nucleophilic attack of the enamine tautomer 19a of 3,4-dihydroisoquinoline 19 to the carbonyl carbon atoms of the anhydrides 5–7 followed by an anhydride

Recent synthesis of thietanes

• Jiaxi Xu

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

• in low to good yields by the reaction of 2-(1-haloalkyl)oxiranes 142 and 147 with ammonium monothiocarbamates 148 as the sulfur nucleophiles. First, a nucleophilic ring-opening of the oxiranes 142 and 147 by monothiocarbamates 148 gave rise to the S-(γ-halo-β-hydroxyalkyl)carbamates 149 with release

• -haloalkyl)thiiranes with various nucleophiles, nucleophilic ring expansion of thiiranes with sulfur ylides, and the electrophilic ring expansion of thiiranes with carbenes generated from sulfur ylides under the catalysis of transition-metal catalysts. 4.1.1 Synthesis via nucleophilic ring expansion of 2-(1

• -haloalkyl)thiiranes: A thiirane–thietane rearrangement took place upon the interaction of (1-haloaklyl)thiiranes 398 with hard and weak nucleophiles (:Nu−) in the presence of a base. It was an efficient method for the preparation of 3-substituted thietanes 400 from (1-haloalkyl)thiiranes 398 through an

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• columns of solid reagents and product receptacle. These components are deployed in a low-cost machine with a design amenable for the automated lab-scale generation of organomagnesium reagents on demand (Figure 1). Organomagnesium compounds are omnipresent reagents that serve as nucleophiles and bases

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• )ethylene-1,2-dicarbonitrile (R = CF3) [8]. Both five-membered spirotetrahydrothiophenes 3 and seven-membered S,N-heterocycles (ketene imines) 4 were observed in the course of these reactions (Scheme 1). The latter products were trapped with suitable nucleophiles (R = CO2Me) or even isolated and identified

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• strong electrophiles and undergo nucleophilic additions with two-electron donors (Scheme 21a) [93][94]. In contrast, radical anions can act as very strong single-electron nucleophiles and are often subject to fragmentation to give a neutral free radical and a charged species (Scheme 21b) [77][95]. When a

• -opening driving force. N-Aryltetrahydroquinolines 34.1 have been intensively studied as a privileged scaffold for N-centred radical cation formations [138]. After iminium formation, formed by subsequent HAT on the amine radical cation, various nucleophiles can add, resulting in diverse functionalizations

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• atoms to engage the ammonium groups of TAPM (see the crystal structure of the F-1a phase). This structure was thermodynamically stable and hinted at a possible activation of water or methanol as nucleophiles by the sulfate anions during the ring opening of epoxides. When the coordinated water was

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• yields and no β-elimination products. The effective removal of the auxiliary using triflic anhydride with LiOH as nucleophile, gave product 177a in good yield. Alternative nucleophiles such as EtOH or methyl esters of amino acids, in the presence of catalytic amounts of CoCl2, afforded product 177b or

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• of the organozinc reagents. To solve this problem, the intermediate of the N-acyl-4-methoxypyridinium salt must be formed in situ and added slowly to the solution of the Cu(OTf)2/L6 complex and dialkylzinc reagent at −78 °C. Several dialkylzinc reagents were found to be effective as nucleophiles in

• ]. Several alkylzirconocenes were examined, resulting in the respective products with 45–93% ee and 20–33% yield. The same group also described the copper-catalysed desymmetrisation of heterocyclic meso compounds via the AAA reaction, once again using alkylzirconocenes as nucleophiles (Scheme 10B). In this

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• biologically active compounds [104]. These compounds can be trapped with nucleophiles to produce the α-amino-substituted compounds, and be employed as substrates for a variety of chemical transformations such as Ugi- and Mannich-type reactions. In this regard, Seeberger and co-workers reported the primary

• ]. Che and co-workers showed that a variety of nucleophiles can be used for the α-functionalization of N-aryltetrahydroisoquinolines using a low Pd-TPFPP loading. This photocatalyst provided the α-aminonitriles in 71–85%, β-nitroamines in 72–83%, β-diester amines in 68–74%, and α-amino phosphonates in 63

• epoxidation agent of an electron-deficient olefin intermediate, which was formed by deaminative Mannich coupling between the imine and nucleophiles such as malononitrile and methyl cyanoacetate (Scheme 64) [109]. Overall, a variety of additional examples of porphyrin-photocatalyzed heteroatom oxidations are

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• ] described NHC–Cu (74)/base 1,2-additions at room temperature of silicon pro-nucleophiles onto aldehydes 81 leading to racemic silyl alcohols 82–87 (Scheme 17B). A detailed mechanistic study revealed that a Cu–Si species is involved, giving intermediate 77, which subsequently undergoes fast Brook

• racemic product 114 (Scheme 22, right) [56]. In 2010, Hoveyda [57] used CuCl along with an NHC ligand (L14) that enabled 1,4-additions of silicon nucleophiles to unsaturated ketones. The best results were obtained at low temperatures, giving both high chemical yields and products with high enantiomeric

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• has allowed to perform a wide range of previously unknown synthetic transformations [19][20][21][22][23][24][25][26][27][28][29]. In these reactions, aryl(vinyl)Cu(III) species [30][31] have been proposed as key intermediates to undergo reactions with a variety of nucleophiles. Fañanás-Mastral and

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• ]. The nucleophilic substitution reactions in thiaselenole 1 with O- and S-centered nucleophiles proceeded regioselectively in an unusual manner at two centers of the seleniranium cation 2: the selenium atom and the carbon atom C2. The classical nucleophilic substitution reaction at the carbon atom C3

• with various nucleophiles (Scheme 4) were accompanied by ring expansion leading to six-membered functionalized dihydrothiaselenines. Furthermore, the reaction of thiaselenole 1 with ammonium thiocyanate also gave the six-membered 2,3-dihydro-1,4-thiaselenin-2-yl thiocyanate (Scheme 4) [46]. It was

• 3. Unusual regio- and stereoselective nucleophilic reactions of thiaselenole 1 at two centers of the seleniranium cation 2. Reactions of thiaselenole 1 with С- and S-centered nucleophiles affording new families of linear unsaturated (Z)-2-[(organylsulfanyl)selanyl]ethenyl vinyl sulfides [31][37][38

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• coordination chemistry, and also valuable protecting or directing groups in catalysis [1][2][3]. 2-Oxazolines are a readily stable class of heterocycles resistant to a range of nucleophiles, bases, or radicals [4][5], which can be easily generated from amino alcohols and carboxylic acids, and from alkenes or

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

• products. Subsequently, benzamidine derivatives with a broad variety of substituents on the benzenoid core were evaluated as the nucleophiles. Benzamidine hydrochloride itself yielded compound 10h with an excellent yield of 93%. A variety of substituted products including electron-donating (compounds 10i–k

• arginine, where the desired pyrimidine 10q was also only observed in trace amounts while the majority of the starting material remained unchanged. Synthesis of fluorinated aminopyrazoles As in the cyclocondensation with amidines, the reaction of 8 with other bifunctional nucleophiles could also result in

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• ]. Aziridines tolerate nucleophiles because chain growth requests the ammonium ion [93][94][95][96]. On the other hand, chain propagation includes the carbocation in the case of oxiranes and oxetanes [92]. More of interest can be seen absorbers, which do not follow such reaction routes. Scheme 7 depicts a

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

• nucleophiles compared to organometallic or metal phosphides generated through metalation processes. Hayashi et al. [66] used tris(trimethylsilyl)phosphine to control the nucleophilic substitution in the preparation of P,N-(phosphino)triazine ligands (Scheme 5). It was shown that the use of other nucleophiles

• from α-C–H bond activation in heterocycles The α-position to a heteroatom in a cyclic compound is activated because of the difference in electronegativity with carbon. This presents an opportunity to readily generate organometallic nucleophiles. Chelucci et al. [71] used this fact to synthesize the

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• nucleophiles to electron-deficient alkenes (Michael acceptors) represents an efficient and attractive methodology for providing a wide range of relevant chiral molecules. In order to increase the attractiveness of this useful catalytic transformation, some Michael acceptors bearing challenging electron

• controlling multiple stereogenic centers in a minimum number of steps is nowadays one of the most important challenges in organic chemistry for the synthesis of complex chiral molecules. The transition metal (TM)-catalyzed enantioselective conjugate addition (ECA) of nucleophiles to electron-deficient alkenes

• . First, the hardness of the involved organometallic reagents has to be considered in order to overcome or limit undesirable side reactions. Although the main role of copper is to form a transient organocuprate reactive species with the hard nucleophiles to avoid the formation of the nondesired 1,2

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• -catalyzed allylic substitution. Keywords: aldehyde; copper; copper catalysis; cross-coupling; palladium; synthetic method; Introduction α-Alkoxy-substituted carbanions (α-alkoxyalkyl anions) are useful C(sp3) nucleophiles for the construction of alcohol units found in a majority of pharmaceuticals

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• , N9B 3P4, Canada, Department of Chemistry, Oakland University, 146 Library Drive, Rochester, Michigan 48309-4479, USA 10.3762/bjoc.16.1 Abstract Dicobalt hexacarbonyl nucleoside complexes of propargyl ether or esters of 5-substituted uridines react with diverse C-nucleophiles. Synthetic outcomes

• -acetate hexacarbonyl dicobalt complexes and a Lewis or Brønsted acid. A range of heteroatom nucleophiles have been incorporated into alkyne dicobalt complexes by this chemistry [34][35][36][37][38][39][40]. However, reactions with carbon-based nucleophiles provide an opportunity to access the structurally

• diverse products via formation of C–C bonds. Nucleophiles as diverse as electron-rich arenes or heteroarenes [41][42], alkenes [43], allylmetalloids [44][45][46], enol derivatives [47][48], and organometallics [49] are suitable for the Nicholas reaction. Allenic byproducts are rarely seen, and

Regioselectivity of glycosylation reactions of galactose acceptors: an experimental and theoretical study

• Enrique A. Del Vigo,
• Carlos A. Stortz and
• Carla Marino

Beilstein J. Org. Chem. 2019, 15, 2982–2989, doi:10.3762/bjoc.15.294

• functions describe better soft–soft interactions between nucleophiles and electrophiles [8][37][38]. The charge density was calculated for both methods using the Merz–Singh–Kollman scheme (MK) [39][40]. For the calculation of Fukui functions, besides the known computation of differences in atomic charges

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• sarcosine moiety could be obtained. To overcome the high reactivity of the Dha moiety towards nucleophiles, we engaged in an alternative synthetic strategy towards the tripeptide thioester carrying the native sequence ᴅ-Ala-Dha-Sar by designing a convergent synthesis to mutasynthon 14 (Scheme 2). First, Boc

Iodine-mediated hydration of alkynes on keto-functionalized scaffolds: mechanistic insight and the regiospecific hydration of internal alkynes

• Zachary Lee,
• Brandon R. Jones,
• Nyochembeng Nkengbeza,
• Michael Phillips,
• Kayla Valentine,
• Alexis Stewart,
• Brandon Sellers,
• Nicholas Shuber and
• Karelle S. Aiken

Beilstein J. Org. Chem. 2019, 15, 2747–2752, doi:10.3762/bjoc.15.265

• promise for further development of the reaction. The iodo group is an excellent leaving group and therefore, the generation of α-substituted hydration products through the addition of suitable nucleophiles to the reaction mixture is a strong possibility. Having proven the existence of the α-iodo

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• and their metal complexes are considered to be efficient precursors for design and selection of new PDT agents, since their reactivity toward various nucleophiles provides a simple, selective and general access to the functionalized derivatives [32][33][34]. Considering the promise of porphyrins and

AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• employment of isoxazole nucleophiles in gold-catalyzed formal [3 + 2] cycloaddition reaction of ynamides [31][32], and zinc-catalyzed the reaction of ynol ethers [33], giving the respective multi-substituted pyrrole derivatives efficiently (Scheme 2a) [34][35]. The reaction proceeds via an α-imino gold

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• -triflyl-propiolamides 1 with N- and P-nucleophiles. Tf = SO2CF3. Synthesis of betaines 3 by a three-component reaction. N-triflylpropiolamides 1: R = Ph (a), 4-Cl-C6H4 (b), t-Bu (c), n-Bu (d), cyclopropyl (e), SiMe3 (f). See Figure 1 for products. Unexpected synthesis of E-3o. Betaines 3 from propiolic