60435-70-3Relevant articles and documents
Application of Trimethylgermanyl-Substituted Bisphosphine Ligands with Enhanced Dispersion Interactions to Copper-Catalyzed Hydroboration of Disubstituted Alkenes
Xi, Yumeng,Su, Bo,Qi, Xiaotian,Pedram, Shayun,Liu, Peng,Hartwig, John F.
supporting information, p. 18213 - 18222 (2020/12/04)
We report the incorporation of large substituents based on heavy main-group elements that are atypical in ligand architectures to enhance dispersion interactions and, thereby, enhance enantioselectivity. Specifically, we prepared the chiral biaryl bisphosphine ligand (TMG-SYNPHOS) containing 3,5-bis(trimethylgermanyl)phenyl groups on phosphorus and applied this ligand to the challenging problem of enantioselective hydrofunctionalization reactions of 1,1-disubtituted alkenes. Indeed, TMG-SYNPHOS forms a copper complex that catalyzes hydroboration of 1,1-disubtituted alkenes with high levels of enantioselectivity, even when the two substituents are both primary alkyl groups. In addition, copper catalysts bearing ligands possessing germanyl groups were much more active for hydroboration than one derived from DTBM-SEGPHOS, a ligand containing 3,5-di-tert-butyl groups and widely used for copper-catalyzed hydrofunctionalization. This observation led to the identification of DTMGM-SEGPHOS, a bisphosphine ligand bearing 3,5-bis(trimethylgermanyl)-4-methoxyphenyl groups as the substituents on the phosphorus, as a new ligand that forms a highly active catalyst for hydroboration of unactivated 1,2-disubstituted alkenes, a class of substrates that has not readily undergone copper-catalyzed hydroboration previously. Computational studies revealed that the enantioselectivity and catalytic efficiency of the germanyl-substituted ligands is higher than that of the silyl and tert-butyl-substituted analogues because of attractive dispersion interactions between the bulky trimethylgermanyl groups on the ancillary ligand and the alkene substrate and that Pauli repulsive interactions tended to decrease enantioselectivity.
Ruthenium(II)-Catalyzed β-Methylation of Alcohols using Methanol as C1 Source
Kaithal, Akash,Schmitz, Marc,H?lscher, Markus,Leitner, Walter
, p. 5287 - 5291 (2019/05/28)
Selective introduction of methyl branches into the carbon chains of alcohols can be achieved with low loadings of ruthenium precatalyst [RuH(CO)(BH4)(HN(C2H4PPh2)2)] (Ru-MACHO-BH) using methanol both as methylating reagent and as reaction medium. A wide range of structurally divers alcohols was β-methylated with excellent selectivity (>99 %) in fair to high yields (up to 94 %) under standard conditions, and turnover numbers up to 18,000 could be established. The overall reaction rate of the complex catalytic network appears to be governed by interconnection of the individual subcycles through availability of the reactive intermediates. The synthetic procedure opens pathways to important structural motifs following the Green Chemistry principles.
Synthesis and fungicidal activity of 2-methylalkyl isonicotinates and nicotinates
Huras, Bogumi?a,Zakrzewski, Jerzy,Krawczyk, Maria,Bombińska, Danuta,Cieniecka-Ros?onkiewicz, Anna,Michalczyk, Alicja
, p. 509 - 517 (2017/02/15)
Abstract: Homologs and analogs of 2-methylheptyl isonicotinate (new, natural antifungal and antibacterial antibiotic isolated from Streptomyces sp. 201): racemic 2-methylalkyl isonicotinates 4 and nicotinates 5 and enantiomerically enriched in the R and S isomers, 2-methylpentyl isonicotinate and nicotinate were obtained. Fungistatic activity of the compounds was evaluated. Nicotinates 5a–c show significant activity against phytopathogenic fungi: Fusarium culmorum, Phytophthora cactorum, Rhizoctonia solani. The activity of the enantiomerically enriched compounds was comparable to the activity of racemic ones. There was no significant difference in fungistatic activity between the enantiomerically enriched R and S isomers. Investigated compounds and their oxalates have proven to be active against chalkbrood disease caused by fungal species Ascosphaera apis. The activity of the nicotinates 5a and 5b and oxalates 5a–c against Ascosphaera apis was higher than the activity of oxalic acid itself. Especially high activity was shown for 2-methylbutyl nicotinate 5a and oxalate of 2-methylpentyl nicotinate 5b. Graphical abstract: [InlineMediaObject not available: see fulltext.]
