182365-57-7Relevant academic research and scientific papers
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.
One-pot sequential 1,4- and 1,2-reductions of α,β-unsaturated δ-lactones to the corresponding δ-lactols with CuCl and NaBH 4 in methanol
Matsumoto, Yasunobu,Yonaga, Masahiro
supporting information, p. 1764 - 1768 (2014/08/05)
An efficient, one-pot method for the highly chemoselective synthesis of δ-lactols from α,β-unsaturated δ-lactones using CuCl and NaBH4 in methanol was developed. Georg Thieme Verlag Stuttgart. New York.
Iridium-catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of syngas
Olsen, Esben P. K.,Madsen, Robert
supporting information, p. 16023 - 16029 (2013/02/22)
A new iridium-catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooctene) and racemic 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (rac-BINAP) in a mesitylene solution saturated with water. A catalytic amount of lithium chloride was also added to improve the catalyst turnover. The reaction has been applied to a variety of primary alcohols and gives rise to products in good to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)-BINAP species. First, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom.
Optically active γ-hydroxy sulfone Julia reagents for the synthesis of peptidyl olefin peptidomimetics
Mirilashvili, Sima,Chasid-Rubinstein, Naama,Albeck, Amnon
supporting information; experimental part, p. 3461 - 3464 (2009/04/14)
Peptidyl olefin peptidomimetics serve as biologically active compounds or as intermediates for other peptidyl isosteres. We developed a chemoenzymatic stereoselective approach to optically active γ-hydroxy sulfones to be assembled into peptidyl olefins by the Julia reaction. Key enzymatic hydrolysis of prochiral diesters to the corresponding hydroxy esters introduces optical activity. The sequence of the subsequent chemical reactions, either protection-hydrolysis-functionalization or functionalization-hydrolysis- protection, determines the absolute stereochemistry of the final sulfone building block. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Chemoenzymatic synthesis of enantiomerically enriched α-chiral 3-oxy-propionaldehydes by lipase-catalyzed kinetic resolution and desymmetrization
Wiktelius, Daniel,Larsson, Emma K.,Luthman, Kristina
, p. 2088 - 2100 (2007/10/03)
Enantiomerically enriched phenylalanine- and leucine aldehyde analogues have been prepared by lipase catalyzed desymmetrization or kinetic resolution of 1,3-propanediol derivatives as key steps. Observations of unusual enantioselectivity were made, and mo
Stereoselective Epoxidation of Phe-Gly and Phe-Phe Vinyl Isosteres
Jenmalm, Annika,Berts, Wei,Li, Yi-Lin,Luthman, Kristina,Csoeregh, Ingeborg,Hacksell, Uli
, p. 1139 - 1148 (2007/10/02)
Novel Phe-Gly and Phe-Phe isosteres have been synthesized.Vinylic isosteres of Phe-Gly and Phe-Phe were prepared by facile Julia reactions, and the resulting stereoisomers were isolated and epoxidized (m-chloroperbenzoic acid).Observed stereoselectivities
