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

• a suitable Michael acceptor 24.2 to obtain the corresponding allylation product 24.3 after a desulfonylation. Enones can also be subject to SET reductions through photoredox catalysis, and this can lead to [2 + 2] cycloadditions [2][108]. Similar intermediates can also be generated through the

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• ], alkynation [17][18], or allylation [19]), this method has certain drawbacks, most importantly the frequent requirement of superstoichiometric amounts of an oxidant. Hence, alternative methods were investigated and photoredox catalysis proved to be a viable option [20][21][22]. By now, several different

• reaction time was kept at 6 h, or was even shortened to 3 h for 6,7-dimethoxy-N-phenyl-THIQ (products 37 and 38). Allylation of the unsubstituted phenyl-THIQ was again more efficient compared to the dimethoxylated substrate. Based on previous reports [45][47][52], we propose the following mechanism for the

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• -metal-catalyzed transformations were needed to achieve the total synthesis of des-epoxy-amphidinolide N, including a palladium asymmetric allylic alkylation (Pd-AAA), a Mukaiyama aldol reaction (with Sn), and a Krische allylation (with Ir) [72]. As special feature of this procedure, an Evans aldol

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• catalysts in a similar transformation [17]. In another study, Reiser and co-workers described a related allylation process of organic halides with allyltributyltin in the presence of [Cu(I)(dap)2]Cl as the catalyst [16]. This reaction was applied to a broad range of substrates, including a para-nitrophenyl

• allylation reaction using the [Cu(I)(dpp)(binc)]BF4 complex (Scheme 16) [32]. The reaction of α-bromomalonates with allyl- and crotylsilanes afforded the allylated products in good yields. To explain the reaction outcome, the authors suggested a reduction of the α-bromomalonate by the excited Cu(I) complex

• allylation of α-haloketones. [Cu(I)(dap)2]Cl-photocatalyzed chlorosulfonylation and chlorotrifluoromethylation of alkenes. Photocatalytic perfluoroalkylchlorination of electron-deficient alkenes using the Sauvage catalyst. Photocatalytic synthesis of fluorinated sultones. Photocatalyzed

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

• ) afforded the linear allylation product 3aa with complete regioselectivity. The symmetric secondary allylic carbonate was converted to the corresponding homoallylic alcohol derivative in 50% yield (3af). To gain understanding into the mechanism of this synergistic palladium/copper-catalyzed allylic cross

Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

• Thomas J. Cogswell,
• Craig S. Donald and
• Rodolfo Marquez

Beilstein J. Org. Chem. 2020, 16, 135–139, doi:10.3762/bjoc.16.15

• described above. Rewardingly, Hosomi–Sakurai allylation of the conjugated imine intermediate proceeded to afford the desired diene 10 in working yield (35%). The formation of diene 10 is significant as the corresponding α,β-enones and α,β-enals undergo exclusive conjugate addition under Hosomi–Sakurai

Indium-mediated C-allylation of melibiose

• Christian Denner,
• Manuel Gintner,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2019, 15, 2458–2464, doi:10.3762/bjoc.15.238

• Christian Denner Manuel Gintner Hanspeter Kahlig Walther Schmid Institute of Organic Chemistry, University of Vienna, Währinger Straße 38, A-1090, Vienna, Austria 10.3762/bjoc.15.238 Abstract The indium-mediated allylation reaction has been applied to melibiose, a disaccharidic substrate. This

• the elongated unit at the reducing end of the disaccharide. Keywords: carbohydrates; C–C bond formation; indium-mediated allylation; melibiose; ozonolysis; Introduction The tin and indium-mediated allylation (IMA) proved to be useful synthetic tools for the chain elongation of unprotected

• reported for the first time a tin-mediated allylation of unprotected carbohydrates followed by ozonolysis allowing for easy accessibility of the corresponding elongated sugars [2]. In the same year, Chan and Li introduced indium for the allylation of aldehydes and furthermore demonstrated the applicability

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

Synthesis and biological evaluation of truncated derivatives of abyssomicin C as antibacterial agents

• Leticia Monjas,
• Peter Fodran,
• Johanna Kollback,
• Carlo Cassani,
• Thomas Olsson,
• Maja Genheden,
• D. G. Joakim Larsson and
• Carl-Johan Wallentin

Beilstein J. Org. Chem. 2019, 15, 1468–1474, doi:10.3762/bjoc.15.147

• intermediates, building blocks 4 and 5 (4, R = Me and 5, R = CH2CH2Ph) were synthesized starting with allyldioxazaborolidine 11, an allyl-transfer reagent that was prepared as previously reported (Scheme 3) [27]. Allylation of methyl pyruvate (12) or 13 (synthesized from dimethyl oxalate and phenethylmagnesium

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

• Yang Liu,
• Julie Oble and
• Giovanni Poli

Beilstein J. Org. Chem. 2019, 15, 1107–1115, doi:10.3762/bjoc.15.107

• -2-cycloalkenones, simply differing on the reaction temperature, are disclosed. These domino transformations allow C–C/O–C or C–C/C–C [3 + 2] annulations at will, via an intermolecular Pd-catalyzed C-allylation/intramolecular O- or C-1,4-addition sequence, respectively. In particular, exploiting the

• -one bis-nucleophiles. Keywords: 1,4-addition; annulation; decarboxylation; palladium; Pd-catalyzed allylation reaction; Introduction The development of new strategies for the synthesis of complex carbocyclic and heterocyclic structures remains a general topic for the synthetic chemists [1]. In the

• , resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxicarbonyl derivatives are used as bis-nucleophile and bis-electrophile partners, respectively. This process involves an intermolecular Pd(0)-catalyzed C-allylation (Tsuji–Trost reaction)/intramolecular nitrogen 1,4-addition sequence (Scheme 1

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• -selective protein modification through aqueous CM [83], thus expanding the catalytic repertoire of protein modification with transition-metal catalysts [84][85][86][87]. A variant of subtilisin from Bacillus lentus containing a single cysteine (SBL-S156C) was modified by direct allylation to install an

Convergent synthesis of the pentasaccharide repeating unit of the biofilms produced by Klebsiella pneumoniae

• Arin Gucchait,
• Angana Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2019, 15, 431–436, doi:10.3762/bjoc.15.37

• -4,6-O-benzylidene-β-D-glucopyranoside (9). Compound 9 was treated with benzyl bromide in the presence of sodium hydride [20] to give O-benzylated derivative 10 in 90% yield in two steps, which on de-O-allylation by treatment with palladium chloride [21] furnished 2-azidoethyl 2-O-benzyl-4,6-O

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• compounds, which led again to oxy-Cope rearranged or [4 + 3]-cycloaddition products using rhodium catalysts [14][28][29][30], or to a C2-allylation of furan with gold catalysts [31]. Finally, to compare the reactivity of cyclopropenes and vinyldiazo compounds, we probed the reaction of 1a with 1,4

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• basic hydrolysis of the formate to afford the acid (2S,3R)-61. Its allylation provided the ester (2S,3R)-62, a protected precursor of 3-hydroxyglutamate, from which (2S,3R)-2 can be prepared by catalytic hydrogenolysis (Scheme 15) [67]. 4-Hydroxyglutamic acids All enantiomers of 4-hydroxyglutamic acid

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• -1-enyl)coumarins 16 were isolated in high overall yields and E-selectivities. Allylation of phenols 16 furnished the RCM precursors 17, which underwent the tandem RCM/allylic oxidation sequence to compounds 15 in fair yields (Table 5). All pyran-2-one-annellated coumarins 15 synthesized in the

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• product 11 (64%). Having the trimerized product 11, we attempted to open the norbornene system due to the fact that not all norbornene rings open up during RCM to generate propellane derivative. After allylation, RCM is not a clean reaction and it gave a mixture of the C3-symmetrical compounds. Therefore

• -allylation in the presence of NaHMDS (1 M solution in THF) at −75 °C to deliver the hexaallyl derivative 20 in 84% yield. Then, RCM in the presence of G-II catalyst in CH2Cl2 under nitrogen atmosphere gave the propellane moieties bearing C3-symmetric product 21 in good yield (91%). Its structure was

• . Synthesis of hexaallyl product 20 Based on the earlier procedure of allylation, compound 19 (336 mg, 0.29 mmol) was treated with NaHMDS (2.3 mL of 1 M solution in THF, 2.39 mmol) and allyl bromide (0.14 mL, 1.93 mmol) for 17 h to deliver hexaallyl product 20 after silica gel column chromatography (20% EtOAc

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• diiodobenzene 11 using allylboronate ester 12 via a SM-type allylation sequence [32]. Next, compound 13 was exposed to Grubbs 1st generation (G-I) catalyst 1 to effect the ring-closure to produce tetrahydronaphthalene derivative 14 (92%). Subsequently, aromatization of compound 14 was accomplished with 2,3

• respect, the key building block 29 was derived by employing a sequential O-allylation and CR, then again O-allylation, and CR [35] starting with a commercially available 6-bromo-2-naphthol (27). Subsequently, the diallyl derivative 29 was exposed to G-II catalyst 2 to deliver a ring-closure product 30 (83

• derivative 75 [41]. To this end, iodoacetanilide 71 was subjected to SM coupling in the presence of allyboronate ester 12 to give ortho-allylacetanilide (72), which was further modified by N-allylation with allyl bromide (28) to offer a mixture of diallyl compound 73a (82%) and isomerized product 73b (8

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• Negishi coupling with aryl bromide, affording the corresponding sterically congested alkene 17b-Ar in 56% yield after two steps. The Negishi coupling with benzyl chloride and the Cu-catalyzed allylation of allyl bromide also afforded the corresponding products 17b-Bn and 17b-Allyl, respectively, in good

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• . Co(III)-catalyzed switchable hydroarylation of alkyl alkenes with indoles. Co(III)-catalyzed C2-allylation of indoles. Co(III)-catalyzed ortho C–H alkylation of arenes with maleimides. Co(III)-catalyzed hydroarylation of maleimides with arenes. Co(III)-catalyzed hydroarylation of allenes with arenes

Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation

• Mrunesh Koli,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193

• temperature ionic liquid (RTIL), [bmim][Br] has been found to be a superior medium for the Bi-mediated Barbier-type allylation of aldehydes compared to other conventional solvents. It plays the dual role of a solvent and a metal activator enabling higher yields of the products in a shorter reaction time using

• stoichiometric/near-stoichiometric amounts of reagents. Plausibly, [bmim][Br] activates Bi metal by a charge transfer mechanism. The 1H VT-NMR studies suggested that both the allylating species, allylbismuth dibromide and diallylbismuth bromide, are generated in situ. Keywords: allylation; bismuth; [bmim][Br

• ]; ionic liquid; Introduction The metal-mediated Barbier-type allylation of aldehydes has drawn considerable attention, because the resultant homoallylic alcohols are versatile intermediates for natural product synthesis [1][2][3][4][5][6][7]. The reaction, carried out in organic solvents, water, mixed

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• cyclopentane 5, a functionalized key intermediate, is presented. Compound 5 is involved in hydrolysis, α-allylation at C-8 and α-methylation at C-10 stereoselectively from the convex face. Then it is subjected to cross metathesis to give α,β-unsaturated ketone 11 as precursor in the total synthesis of

• hyperireflexolide A. Keywords: alkylation; allylation; cross metathesis; hyperireflexolide A; spiroterpene; Introduction Hyperireflexolide A (1) [1] is a spiroterpenoid, isolated from hypericum reflexum, plants of the genus hypericum (Figure 1). Hyperireflexolide A is widely used in folk medicine, displays

• with 2-bromopropene followed by lactonization. Enone 3 could be synthesized from 4 by installation of the methyl group at C-10 followed by cross metathesis reaction. Compound 4 could be obtained from the γ-lactone-fused cyclopentane 5 by deprotection of C-9 followed by allylation at C-8. Previously, we

Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion

• Eric Detmar,
• Valentin Müller,
• Daniel Zell,
• Lutz Ackermann and
• Martin Breugst

Beilstein J. Org. Chem. 2018, 14, 1537–1545, doi:10.3762/bjoc.14.130

• ) to yield complex 5a. In contrast to previous computational studies on manganese(I)-catalyzed fluoro-allylation reactions where β-fluoride and HF eliminations played an important role [41], similar reactions involving amine eliminations seem to be not relevant in this reaction. Furthermore, a

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• selectivity of ortho-lithiation could be tuned by changing the alkyllithium reagent employed. The performance of four inherently chiral bidentate calix[4]arene ligands in the asymmetric Tsuji–Trost allylation reaction (Scheme 10) has been evaluated and compared to that of the planar model ligands. Inherently

• applied in the palladium-catalyzed Tsuji–Trost allylation reaction. BINOL-derived calix[4]arene-diphosphite ligands. Inherently chiral calix[4]arene 43 containing a diarylmethanol structure. Calix[4]arene-based chiral primary amine–thiourea catalysts. Novel prolinamide organocatalysts based on the calix[4

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

• Romain Sallio,
• Stéphane Lebrun,
• Frédéric Capet,
• Francine Agbossou-Niedercorn,
• Christophe Michon and
• Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

• with a tert-butyl increased significantly the diastereoselectivity of the reaction with 62% de (Table 2, entry 3). No de improvements resulted from the use of catalysts 18d,e which were modified by methylation or allylation of the cinchoninium alcohol fragment (Table 2, entries 4 and 5). While using

Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• to provide the desired 2-aminoheptenoic acid derivative 11. Several syntheses of this important amino acid have appeared which include Lubell’s palladium-catalyzed allylation [15], Riera’s asymmetric epoxidation protocol [16], Rich’s enolate amination [17] and Hruby’s asymmetric alkylation [18] of a