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

• those obtained with GII were obtained. In the presence of a non-bulky primary amine such as n-butylamine, the bis-aminobenzylidene 17 was formed and complete decomposition was noticed after 12 h at rt yielding ruthenium complex 18 and amine 10. In the presence of secondary amines b and c and sp2 amine d

• mechanism involving a deprotonation of the metallacyclobutane intermediate 23 was hypothesized. The resulting anionic ruthenium complex 24 would be protonated and, after elimination, alkene 22 and unidentified ruthenium complexes would be produced (Scheme 10). According to these mechanistic investigations

• , several pathways are involved in the amine-induced catalyst decomposition depending on the nature of the amine and of the ruthenium complex. Non-bulky primary amines can attack directly benzylidene species and are responsible for the fast degradation of the catalyst. In the case of a phosphine-containing

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• concentrated on the side chain of the vinyl group [24][25][26][27] or applications of 2-fluoroalkenes [28][29][30]. As an exception, the reaction of the Grubbs 2nd generation catalyst with 1,1-difluoroethene gave an isolable difluoromethylene-containing ruthenium complex with very poor catalytic activity [31

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

• this increased stability diminished the activity of 21 when compared to 15 [52]. In 2000, Dowden [53] and co-workers reported the use of a polystyrene-supported ruthenium complex 24 (Scheme 5); a variation of the Hoveyda–Grubbs catalyst. It could be reused up to 5 times without loss of activity and

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• residues are known to induce ruthenium-complex decomposition, and increase purification complexity [25]. Moreover, in a previous report regarding the synthesis of a dormant ruthenium catalyst bearing a chelating carboxylate ligand, spontaneous chloride/carboxylate exchange with elimination of HCl has been

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• ruthenium complex 11 which contain (1R,2R)- or (1S,2S)-N-tosyl-1,2-cyclohexanediamine as chiral ligand (Figure 2). The reaction was carried out in acetonitrile using an azeotropic mixture of formic acid/triethylamine as hydrogen source with 50:1 substrate to catalyst ratio. Under these conditions the

• regardless of the solvent used, with the exception of acetonitrile (Table 1, entries 8–10). In CH3CN this catalyst is inactive and the product was not formed. The solvent effect on the chemical yield was similar to that observed with catalyst 11 (Table 1). Finally, the ruthenium complex 13 modified with

Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity

• Karolina Żukowska,
• Eva Pump,
• Aleksandra E. Pazio,
• Krzysztof Woźniak,
• Luigi Cavallo and
• Christian Slugovc

Beilstein J. Org. Chem. 2015, 11, 1458–1468, doi:10.3762/bjoc.11.158

• as starting from a pyridine containing the ruthenium complex, which is known to increase the cis-content, or increasing the exposure time of the catalyst up to 8 h in microwave at 140 °C in CDCl3 resulted in limited success. The formyl-substituted complex 15 underwent isomerization, but only a

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• was used [181]. The reaction time is 18 h at 90 °C, the yields of α-ketoesters vary from 42 to 88%. The unusual C–O cross-coupling of primary alcohols 184 with secondary alcohols 185 in the absence of oxidants was performed in the presence of ruthenium complex 186 as the catalyst; the reaction

A concise synthesis of 3-(1-alkenyl)isoindolin-1-ones and 5-(1-alkenyl)pyrrol-2-ones by the intermolecular coupling reactions of N-acyliminium ions with unactivated olefins

• Nianhong Lu,
• Lihong Wang,
• Zhanshan Li and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 192–200, doi:10.3762/bjoc.8.21

• rare. Lee recently reported a coupling of alcohols with olefins catalyzed by a ruthenium complex to give alkyl-substituted alkenes through the formation of Csp3–Csp2 bonds [10]; Liu reported the FeCl3/TsOH catalyzed coupling of diarylmethanol with styrenes to afford the alkyl-substituted styrenes [11

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

• both cis-2-butene-1,4-diyl diacetate (2) and the diol 8 (Table 6). Whilst the conversion of methyl oleate (1) with the protected diol 2 was nearly quantitative using 1.5 mol % of the ruthenium complex [Ru]-7 at 50 °C within 5 h (Table 6, entry 1), comparative results in the cross-metathesis of oleic

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• ]. a) Acceleration of ring-closing enyne metathesis by the allylic hydroxy group [23]. b) Proposed mode of action by the allylic hydroxy group in this reaction. a) Effect of the hydroxy group on the rate and steroselectivity of ROCM [24]. b) Proposed H-bonded ruthenium complex for stereoselective ROCM

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

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

• described in 1998 by Dixneuf et al. [65], who used the cationic allenylidene ruthenium complex 14 (Scheme 4) for the ene-yne RCM of propargylic allyl ethers into 3-vinyl-2,5-dihydrofurans. The best conditions reported for this reaction were the irradiation of a toluene solution of 14 and substrate with an

• , isolated from the monomer. Light activated metathesis of trans-2-pentene. Light induced generation of metathesis active species 2. Proposed mechanism for photoactivation of sandwich complexes. Photopromoted ene-yne RCM by cationic allenylidene ruthenium complex 14. Ruthenium NHC complexes for PROMP

Large- scale ruthenium- and enzyme- catalyzed dynamic kinetic resolution of (rac)-1-phenylethanol

• Krisztián Bogár,
• Belén Martín-Matute and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2007, 3, No. 50, doi:10.1186/1860-5397-3-50

• reaction is performed on a 1 mmol scale, 4 mol% of ruthenium complex 1 is used for an efficient reaction.[32][34] We believe that the need of this high catalyst loading is due to a fast decomposition of the ruthenium active intermediates in the presence of small amounts of molecular oxygen. To test this

• obtained in 87% yield (corresponds to 1.43 kg). The remaining alcohol had an ee of 19%, demonstrating the high racemization ability activity of ruthenium complex 1. Conclusion In this article, some of the scale-up issues in the ruthenium- and enzyme-catalyzed DKR of (rac)-1-phenylethanol were investigated