79253-39-7Relevant 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.
A practical, enantioselective synthesis of the fragrances canthoxal and silvial, and evaluation of their olfactory activity
Beghetto, Valentina,Scrivanti, Alberto,Bertoldini, Matteo,Aversa, Manuela,Zancanaro, Aurora,Matteoli, Ugo
, p. 272 - 278 (2015/05/05)
The fragrances (S)-(+)- and (R)-(-)-canthoxal [(S)-(+)- and (R)-(-)-3-(4-methoxyphenyl)-2-methylpropanal] and (+)- and (-)-Silvial [(+)- and (-)-3-(4-isobutylphenyl)-2-methylpropanal] have been synthesized in high enantiopurity via a simple fou
Highly enantioselective hydrogenation of 2-substituted-2-alkenols catalysed by a ChenPhos-Rh complex
Wang, Quanjun,Liu, Xueying,Liu, Xian,Li, Bin,Nie, Huifang,Zhang, Shengyong,Chen, Weiping
, p. 978 - 980 (2014/01/06)
Highly enantioselective hydrogenation of a variety of 2-substituted-2- alkenols has been achieved using a ChenPhos-Rh complex as catalyst, giving ≥99% ee for most substrates. Optically active antifungal agent amorolfine was first synthesised using hydrogenation as the key step. This journal is
Acid promoted CIDT for the deracemization of dihydrocinnamic aldehydes with Betti's base
Rosini, Goffredo,Paolucci, Claudio,Boschi, Francesca,Marotta, Emanuela,Righi, Paolo,Tozzi, Francesco
experimental part, p. 1747 - 1757 (2011/02/28)
Racemic α-epimerizable and unfunctionalized aldehydes have been converted into enantiomerically enriched mixtures through a sequence of (i) a conversion into the diastereoisomeric 3-substituted 1-phenyl-2,3-dihydro-1H- naphtho[1,2-e][1,3]oxazines by reaction with the (R)- or (S)-1-(α- aminobenzyl)-2-naphthol (Betti's base), (ii) an acid promoted crystallization-induced diastereoisomer transformation (CIDT), and (iii) a clean cleavage of the dihydro-1,3-naphthoxazinic ring of the enriched diastereoisomer, easily collected by filtration, allowing the recovery of the enantiomerically enriched aldehydes and the chiral auxiliary.
Chemoenzymatic synthesis of (+)-α-polypodatetraene and methyl (5R,10R,13R)-labda-8-en-15-oate
Kinoshita, Masako,Miyake, Takahiro,Arima, Yuusuke,Oguma, Minako,Akita, Hiroyuki
, p. 118 - 123 (2008/09/17)
The reported enzymatic resolution products {acetate of (1S,4aS,8aS)-1,2,3, 4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2- ethylene acetal} (8aS)-5 (>99% ee)] and [(1R,4aR,8aR)-1,2,3,4,4a,5,6,7,8,8a- decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aR)-4 (98% ee) were converted to (+)-α-polypodatetraene (1) and methyl (5R,10R,13R)-labda-8-en-15-oate (2), respectively. For the synthesis of (5R,10R,13R)-2, chiral isoprene congener (3S)-26 corresponding to the right part of 2 was synthesized based on the lipase-assisted resolution of (±)-2-methyl-3- (p-methoxyphenyl)propanol (17).
Enantioselective synthesis of (2R,4'R,8'R)-α-tocopherol (Vitamin E) based on enzymatic function
Nozawa, Masako,Takahashi, Keiko,Kato, Keisuke,Akita, Hiroyuki
, p. 272 - 277 (2007/10/03)
Syntheses of (S)-chroman-2-carboxaldehyde congener 1 and (S)-chiral isoprene unit 3 were achieved based on the enzymatic acetylation of (±)- chroman-2-methanol 6 and (±)-(2,3)-anti-2-methyl-3-(p-methoxyphenyl)-1,3- propane diol 12, respectively. Synthesis of the side-chain part corresponding to (3R,7R)-3,7,11-trimethyldodecan-1-ol 27 was achieved by the coupling reaction of (S)-3 and (R)-3,7-dimethyloctyl iodide 4. The Wittig reaction of (3R,7R)-phosphonium salt 2 derived from (3R,7R)-27 and (S)-1 gave the olefin 28 which was subjected to catalytic hydrogenation to afford (2R,4'R,8'R)-α- tocopherol.
A Study of Enantioselective Reduction of para-Substituted 2-Methyl-cinnamaldehydes by Baker's Yeast
Sunjic, Vitomir,Majeric, Maja,Hamersak, Zdenko
, p. 643 - 660 (2007/10/03)
Reduction of a series of para-substituted 2-methyl-cinnamaldehydes (1-7) at 20°C and at pH = 2-3 afforded S-enantiomers of saturated alcohols 8-14 in 20-80% yield and 75 - ≥ 99% enantiomeric excess (e.e.); at 30°C, lower yields and e.e.s were obtained. Relative rates of the formation of allylic alcohols 15-21, catalyzed by alcohol dehydrogenase (ADH), correlate with the Hammett σ+ values of para-substituents, revealing that a more efficient delocalization of the positive charge on carbonylic carbon slow down the reduction rates, whereas no correlation of the electronic properties of the substituents with the rate of C=C double bond reduction, catalyzed by enoate reductase, is observed. On reduction of 3 by dried yeast in 2H2O, α,β-carbon atoms in 10a bear 2H atoms, in accordance with the previously reported hydrogenation of selectively 2H-labeled cinnamic aldehyde and cinnamic alcohol. The accumulated data indicate that the mechanism of the enone C=C bond reduction that comprises nucleophilic attack of the hydride ion species on the β-carbon in the first step, followed by enantioselective protonation on the α-carbon atom.
A synthesis of (2R,4'R,8'R)-α-tocopherol (vitamin E) side chain
Chen, Cheng Yu,Nagumo, Shinji,Akita, Hiroyuki
, p. 2153 - 2156 (2007/10/03)
Optically pore (3R,7R)-3,7,11-trimethyldodecan-1-ol (16), corresponding to the α-tocopherol side chain, was synthesized by the coupling reaction of a chiral isoprene unit (3S)-9 derived from an enzymatically hydrolyzed product (2S,3S)-2 and a ten-carbon alkylating reagent (R)-13 derived from (R)-(+)-pulegone.
