Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• 20 min at 80 °C using 1 mol % of catalyst 59 [52]. Due to the fact that ethylene formed in the ring-closing metathesis can result in the formation of unstable ruthenium methylidene species, causing degeneration of the metathesis catalyst, the continuous removal of ethylene from the reaction mixture

• synthesis of civetone (69) enabled by metathesis catalyst 68 in a tube-in-tube reactor. Synthesis of macrocyclic olefine 72 by ring-closing metathesis of diene 70. Acknowledgements We acknowledge Lisa Böser (Technische Universität Berlin) and Lorenz Wiese (Freie Universität Berlin) for helpful discussions

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• ; cross metathesis; Hoveyda–Grubbs catalyst; olefin metathesis; RCM; ring-closing metathesis; ring-opening cross metathesis; ROCM; ruthenium metathesis catalyst; styrene; 2-vinylbenzylamine; Introduction Ruthenium-catalysed olefin metathesis reactions have been playing an important role in various fields

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

• ). Catalysts 3 and 4 showed modest activities in the ROMP of substrate 35. In 2006, Grela and co-workers reported the synthesis of the metathesis catalyst 5 also bearing a quaternary ammonium tag [57]. Following their previous studies highlighting the beneficial effect of an electron-withdrawing group (EWG) on

• , while the RCM of 67 reached 20 and 14 TON, respectively, with ArM 3 and catalyst 66. However, ArM 3 decreased the RCM activity of 21 to 4 TON compared to 20 TON with catalyst 66. In 2011, Hilvert and co-workers reported an ArM based on the covalent anchoring of a metathesis catalyst to a small heat

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• and electronic properties of the NHC ligand. Significant advances in ruthenium metathesis catalyst design have been achieved by the introduction of unsymmetrically substituted NHC (uNHC) ligands, namely presenting different substituents at the nitrogen atoms. They offer the possibility of strongly

• beneficial effect on the catalytic activity was observed. Indeed complex 22 revealed a very poor olefin metathesis catalyst, likely as a consequence of the excessive steric hindrance of the adamantyl moiety at the ruthenium center. It is worth to underline that the first Z-selective ruthenium catalyst (23

The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study

• Magdalena Jawiczuk,
• Angelika Janaszkiewicz and
• Bartosz Trzaskowski

Beilstein J. Org. Chem. 2018, 14, 2872–2880, doi:10.3762/bjoc.14.266

• of these effects [47]. To resolve this issue we performed benchmark calculations for standard metathesis catalyst GrI, as well as newly developed catalyst featuring a labile carbodicarbene ligand (as a model of 1–3-GrII) [48]. In the case of GrI we found the Gibbs free energy of initiation in the M06

• experimental values for PCy3 dissociation for these catalysts are 23.0 ± 0.4 and 24 ± 1 kcal/mol for SIMes-containing and IMes-containing systems, respectively [57]. Recently Grubbs synthesized and described also a novel metathesis catalyst featuring a labile carbodicarbene ligand replacing PCy3 [48]. Inspired

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• the case of a metathesis catalyst, so-called artificial metatheases are obtained, which could open new areas of biological applications [19]. The protein as second coordination sphere might take influence on the formation of the metallacyclobutane that was initially postulated by Chauvin [2]. The

• synthesized by Ward [29]. A GH-type second generation olefin metathesis catalyst was modified at the periphery of an NHC ligand with a biotin moiety [46]. The small β-barrel protein avidin (Avi) or streptavidin (Sav) was incubated with the catalyst to give the artificial metalloprotein. This (strept)avidin

Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid

• Jacqueline Pollini,
• Valentina Bragoni and
• Lukas J. Gooßen

Beilstein J. Org. Chem. 2018, 14, 2737–2744, doi:10.3762/bjoc.14.252

• autoclave was charged with the metathesis catalyst Ru-1 (330 mg, 0.55 mmol), CNSL (37.7 g, 110 mmol) and DCM (100 mL) under ethylene atmosphere. The system was evacuated and backfilled with ethylene (5 bar) three times and finally pressurized to 10 bar. The mixture was stirred at 500 rpm at room temperature

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• THF or DME was facilitated [49]. The molybdenum 2,4,6-trimethylbenzylidyne complex [MesC≡Mo{OC(CF3)2Me}3] (Figure 1, MoF6) represents the first alkyne metathesis catalyst capable of effective and highly selective terminal alkyne metathesis [49][51][52][53]. Later, a study was conducted to determine

• by a stoichiometric alkyne metathesis reaction of the ditungsten complex [(t-BuO)3W≡W(Ot-Bu)3] with MeC≡Ct-Bu (Scheme 1) [62]. Even though Schrock’s catalyst V was the most established alkyne metathesis catalyst for many years [63][64], it does not promote terminal alkyne metathesis efficiently and

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

• Krzysztof Skowerski,
• Jacek Białecki,
• Stefan J. Czarnocki,
• Karolina Żukowska and
• Karol Grela

Beilstein J. Org. Chem. 2016, 12, 5–15, doi:10.3762/bjoc.12.2

• ). It was then mechanically removed, providing the colourless product in very good yield (93%) and with low residual ruthenium content (25 ppm, Figure 9C). This level of contamination is higher than in the case of 8-SiO2 or 8-C*, however, we think that immobilisation of a metathesis catalyst on iron is

• an olefin metathesis catalyst, bearing a quaternary ammonium-tagged NHC ligand. This catalyst can be non-covalently immobilised on various organic and inorganic solid supports in a straightforward and universal manner. Depending on the nature of the support chosen, the properties of the resulting

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• compounds even at 0 °C. It was also examined in more demanding systems such as conjugated dienes and polyenes. The catalyst is stable, storable and easy to purify. Keywords: chromane derivatives; metathesis catalyst; nitrogen heterocycles; olefin metathesis; Ru-carbene; Introduction Olefin metathesis is

• olefin metathesis catalyst 9 is reported. The catalyst contains a NHC ligand generated from the imidazolinium salt 14 bearing two symmetrically substituted 6-chromanyl moieties. The catalyst 9 was tested in model CM and RCM reactions and showed an activity comparable or superior to that of the commercial

• ruthenium catalysts. Selected ruthenium metathesis catalyst bearing chromanyl moieties. π-Complex and rutenacyclobutane intermediate with a five-membered ring chelate. Numbering of carbon atoms in the chromanyl moiety. Synthesis of the new NHC precursor. Reagents and conditions: a) HNO3, CH2Cl2, 0 °C, 58

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• influence of pyridine as an additive on the deactivation of the metathesis catalyst has not been yet studied in detail [44]. When reacted with an excess of pyridine, the methylidene adduct 2 obtained from GII led to the formation of inactive complex 16 together with CH3PCy3+Cl−. These products would result

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• catalyst (9, Scheme 3). The reaction of RuCl2(PPh3)3-4 (3) with phenyldiazomethane (7), followed by a phosphine exchange reaction, afforded complex 9 in high yields. Complex 9 has become the most used metathesis catalyst, because of its good activity, relatively good stability to air (storage of 9 has been

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• ]. The ROMP and RCM performance of Fischer-carbene complexes such as 9 are often sluggish and often do not result in high conversions [65][66]. However, these complexes are thermally very inert and economically viable options to other commercially available olefin metathesis catalyst. Furthermore, their

• closing metathesis (RCM) activities in organic and aqueous solvents, as well as their use in the first near-quantitative ROMP procedure in microemulsion to produce stable latexes from DCPD and DCPD/COE mixtures. Results and Discussion Catalyst syntheses We have previously reported olefin metathesis

• catalyst 5 bearing the pH-responsive H2ITap [1,3-bis(N’,N’,2’,6’-tetramethylaminophenyl)-4,5-dihydroimidazol-2-ylidene] ligand containing two NMe2 groups [61]. The addition of HCl to complex 5 results in the protonation of the amino groups to produce a water-soluble dicationic complex. Although the

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• , Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany Institut für Textilchemie und Chemiefaser (ITCF) Denkendorf, Körschtalstr. 26, D-73770 Denkendorf, Germany 10.3762/bjoc.11.178 Abstract The novel dicationic metathesis catalyst [(RuCl2(H2ITapMe2)(=CH–2-(2-PrO)-C6H4))2+ (OTf−)2] (Ru-2

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• conditions to furnish 1c. Interestingly, the tricyclic sulfone 11 was isolated in 60% along with the expected tetracyclic sulfone 1c (32%) and a minor amount of ring-opened product 12 (6%, Scheme 5). A complex mixture of products was obtained when compound 2c was exposed to the metathesis catalyst for a

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• converted to 2-allyl-2-methylcyclohexanone (2) in 85% yield and 88% ee [58] with a catalytic amount of [Pd2(dba)3] and (S)-t-BuPHOX (5, Scheme 1). The allyl ketone was enriched to 98% ee via recrystallization of semicarbazone 33 [59]. Using the Grubbs 2nd generation metathesis catalyst, allyl ketone (−)-2

A modular phosphate tether-mediated divergent strategy to complex polyols

• Paul R. Hanson,
• Susanthi Jayasinghe,
• Soma Maitra,
• Cornelius N. Ndi and
• Rambabu Chegondi

Beilstein J. Org. Chem. 2014, 10, 2332–2337, doi:10.3762/bjoc.10.242

• thank the University of Kansas and the State of Kansas for support of our program. The authors also thank Materia, Inc. for supplying the metathesis catalyst.

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• presence of a metathesis catalyst competes with EYCM. Essentially for this reason, an excess of olefin with respect to the alkyne (usually from 2 to 9 equiv) was always used to favor complete conversion of the latter. Following the first results and to avoid the competing metathetic reactions, it was shown

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• in which dendrimer chemistry can be useful in this direction, and this short review article will indicate the various connections between metathesis reactions and dendrimer chemistry. Review Covalent attachment of the olefin metathesis catalyst to the tethers of the dendrimer periphery The attachment

• of catalysts to dendrimers was mostly focused on the recovery of the catalyst. Only a few metallodendritic carbene complexes with covalent binding of the olefin metathesis catalyst are known. Prior to our involvement only compounds with four branches were known [11][12][13][14] but good recyclability

• benzylidene metathesis catalyst, 1 [23], as the starting point. These reactions provided four generations of new, stable metallodendrimers 2 containing ruthenium-benzylidene fragments at the periphery (Scheme 1) [24][25]. The fourth-generation metallodendrimer containing 32 ruthenium-benzylidene fragments

Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

• Hynek Balcar,
• Tushar Shinde,
• Naděžda Žilková and
• Zdeněk Bastl

Beilstein J. Org. Chem. 2011, 7, 22–28, doi:10.3762/bjoc.7.4

• : alkene metathesis; catalyst immobilization; hybrid catalysts; mesoporous molecular sieves; Ru–alkylidene complexes; Introduction Ru–alkylidene complexes (Grubbs and Hoveyda–Grubbs catalysts, 1 and 2, respectively, Figure 1) belong to the most active and frequently used metathesis catalysts. These

The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

• Arno Behr and
• Jessica Pérez Gomes

Beilstein J. Org. Chem. 2011, 7, 1–8, doi:10.3762/bjoc.7.1

• and an inexpensive base chemical was prepared. Various metathesis catalysts were investigated, disclosing that the Schiff base ruthenium indenylidene catalyst [Ru]-7 bearing a N-heterocyclic carbene ligand, which is an already industrial implemented metathesis catalyst, led to high conversions and

• methyl oleate (1) with cis-2-butene-1,4-diyl diacetate (2) and the self-metathesis of 1. Results of metathesis catalyst activities in the cross-metathesis of methyl oleate (1) with 2.a Results of catalytic investigations of cross-metathesis of 1 with 2 with various [Ru]-7 loadings.a Results of catalytic

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127

• photoinitiated metathesis is indirect activation. Grubbs et al. [79] demonstrated the use of photoacid generators (PAG) 34 and 35 (Figure 13) for the sub-300 nm UV activation of metathesis precatalysts 36 and 37 (Scheme 8). Thus, an acid sensitive olefin metathesis catalyst can be photoactivated by using a PAG

Gelation or molecular recognition; is the bis-(α,β-dihydroxy ester)s motif an omnigelator?

• Peter C. Griffiths,
• David W. Knight,
• Ian R. Morgan,
• Amy Ford,
• James Brown,
• Ben Davies,
• Richard K. Heenan,
• Stephen M. King,
• Robert M. Dalgliesh,
• John Tomkinson,
• Stuart Prescott,
• Ralf Schweins and
• Alison Paul

Beilstein J. Org. Chem. 2010, 6, 1079–1088, doi:10.3762/bjoc.6.123

• and was completely free of triethylamine, which is a very effective ligand and quench for the Grubbs Mark II metathesis catalyst. This was achieved by extensive washing during work-up (water, sat. aq NH4Cl, 1 M HCl, sat. aq K2CO3, water and brine) followed by distillation, bp ~40 °C at 17 mm Hg. Gel