Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• conditions for the metathesis using the 1st generation Grubbs catalyst were attempted without success, but when 2nd generation catalyst was used, the dimerization product 100 was observed (Scheme 20). Despite the yield for macrolide formation, Cousin proposed alternatives for the formal synthesis of 2

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

• generation Grubbs catalyst (GrI) and M1 indenylidene catalyst (Ind). New complexes were formed by replacing one PCy3 phosphine ligand with the cationic NHC 1–3 (Scheme 1). We considered only the dissociative mechanism of initiation, in agreement with the numerous reports on the initiation of Grubbs catalyst

• higher stabilities of dimers on solution (see Supporting Information File 1). First generation Grubbs and M1 indenylidene catalyst In the next step of the study we performed a computational investigation of possible pathways of the initiation of cationic ruthenium catalyst based on the commonly used 1st

Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

• Yulia I. Denisova,
• Maria L. Gringolts,
• Alexander S. Peregudov,
• Liya B. Krentsel,
• Ekaterina A. Litmanovich,
• Arkadiy D. Litmanovich,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2015, 11, 1796–1808, doi:10.3762/bjoc.11.195

• -chloroform mediated by the 1st generation Grubbs’ catalyst Cl2(PCy3)2Ru=CHPh is studied by monitoring the kinetics of carbene transformation and evolution of the dyad composition of polymer chains with in situ 1H and ex situ 13C NMR spectroscopy. The results are interpreted in terms of a simple kinetic two

• cis-cyclooctene because of their substantially different monomer reactivities. Keywords: cross-metathesis; 1st generation Grubbs’ catalyst; interchange reactions; kinetics; multiblock copolymer; Introduction A desired sequence of monomer units in a polymer chain can be achieved not only in the

• noteworthy that the reaction is readily mediated by the 1st generation Grubbs’ catalyst Cl2(PCy3)2Ru=CHPh (Gr-1), which is not suitable for metathesis ring-opening copolymerization of NB and COE. Our approach makes it possible to synthesize statistical multiblock NB-COE copolymers containing up to 50% of

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• resolution in the ester reduction step, enantiopure (+)-21 was obtained. 1st-generation Grubbs catalyst was used for the RCM of (+)-21. It should be noted that the yield of (+)-22 in RCM (10 mol % 2, in benzene) was temperature dependent (88% at room temperature and 98% at 80 °C). Further stereocontrolled

• diastereomer. The nitrogen atom in 25 was then Boc-protected, debenzylated, and allylated to give the diene 26. RCM of the latter with 1st-generation Grubbs catalyst (10 mol % 2, in dichloromethane, at room temperature) provided the pyrrole scaffold 27. Subsequent stereoselective dihydroxylation (OsO4 and 4

• moderate inhibition of β-galactosidase, and α-galacto- and α-mannosidases, respectively. It should be noted that diene 38 did not cyclize in the presence of 1st-generation Grubbs catalyst, even in refluxing toluene, whereas 2nd-generation Grubbs catalyst afforded (in toluene, at 60 °C) the cyclic products