110611-67-1Relevant articles and documents
Investigation of Electrostatic Interactions towards Controlling Silylation-Based Kinetic Resolutions
Zhang, Tian,Redden, Brandon K.,Wiskur, Sheryl L.
, p. 4827 - 4831 (2019)
Electrostatic interactions between a silylated isothiourea intermediate and an ester π system were explored by determining how variations in sterics and electronics affect the selectivity of a silylation-based kinetic resolution. Sterics on the π systems affect the selectivity factors of alkyl 2-hydroxycyclohexanecarboxylates, resulting in a strong correlation of selectivity factors to Charton values. Induction effects of electron-withdrawing substituents on phenyl esters significantly enhance selectivity supporting an edge to face π–π interaction. The linear free energy relationships that were uncovered will aid in future incorporation of intermolecular electrostatic interactions towards controlling asymmetric reactions.
Copper-catalyzed, stereoconvergent,: Cis -diastereoselective borylative cyclization of ω -mesylate- α, β -unsaturated esters and ketones
Zuo, Ya-Jie,Chang, Xiao-Tong,Hao, Zhi-Ming,Zhong, Chong-Min
, p. 6323 - 6327 (2017/08/10)
The Cu(i)-catalyzed stereoconvergent borylative cyclization of ω-mesylate-α,β-unsaturated compounds is facilitated by a simple Cu-bisphosphine catalyst. This reaction provides a novel route to cis-β-boron-substituted five- and six-membered carbocycle and heterocycle esters. Mechanistic studies indicate that stereoconvergence and cis-substitution likely stem from the rapid enolation of the borylcopper adduct with the substrate double bond and the formation of a five-membered intermediate, respectively.
Candida antarctica lipase B-catalyzed reactions of β-hydroxy esters: Competition of acylation and hydrolysis
Forro, Eniko,Galla, Zsolt,Fueloep, Ferenc
, p. 92 - 97 (2013/11/19)
The ester function of ethyl cis-(±)-2-hydroxycyclopentane-1- carboxylate [(±)-1] and ethyl (±)-5-hydroxycyclopent-1- enecarboxylate [(±)-2] was demonstrated to undergo hydrolysis, as a side-reaction, during asymmetric (E > 200) O-acylation with Candida antarctica lipase B (CAL-B) as catalyst and vinyl acetate as acyl donor in t-BuOMe at 30 C. This competition of acylation and undesirable hydrolysis draws attention to CAL-B-catalyzed non-hydrolytic resolutions where the substrates contain any hydrolysable functions. Enantiomerically enriched cis-2-hydroxycyclopentane-1-carboxylic acid (ee = 90%) and 5-hydroxycyclopent-1- enecarboxylic acid (ee = 47%) were prepared through de novo CAL-B-catalyzed hydrolysis of (±)-1 and (±)-2 with added H2O in t-BuOMe at 30 C.
Modular synthesis of the ClickFerrophos ligand family and their use in rhodium- and ruthenium-catalyzed asymmetric hydrogenation
Oki, Hiroshi,Oura, Ichiro,Nakamura, Tatsuhito,Ogata, Kenichi,Fukuzawa, Shin-ichi
experimental part, p. 2185 - 2191 (2010/03/03)
A series of diphosphine ClickFerrophos ligands (CF), based on a triazoleferrocene backbone, was synthesized in a four-step sequence via click chemistry methodology. In addition to the four previously synthesized ligands CF1, CF4, CF7 and CF10, six novel C
ClickFerrophos: New chiral ferrocenyl phosphine ligands synthesized by click chemistry and the use of their metal complexes as catalysts for asymmetric hydrogenation and allylic substitution
Fukuzawa, Shin-Ichi,Oki, Hiroshi,Hosaka, Mitsuteru,Sugasawa, Jun,Kikuchi, Satoshi
, p. 5557 - 5560 (2008/09/17)
The new ferrocenyl P,P- and P,N-ligands 5 and 6 (collectively, "ClickFerrophos") were readily prepared in four steps using Click Chemistry methodology, starting from the commercially available aminoferrocene 1. Rhodium and ruthenium complexes of ClickFerrophos 5 were effective catalysts for the hydrogenation of alkenes and ketones, respectively, producing products with up to 99.7% ee. The analogous palladium complex with 6 worked well for asymmetric allylic alkylation.
Reductions of cyclic β-keto esters by individual Saccharomyces cerevisiae dehydrogenases and a chemo-enzymatic route to (1R,2S)-2-methyl-1-cyclohexanol
Padhi, Santosh Kumar,Kaluzna, Iwona A.,Buisson, Didier,Azerad, Robert,Stewart, Jon D.
, p. 2133 - 2138 (2008/02/11)
Twenty purified dehydrogenases cloned from bakers' yeast (Saccharomyces cerevisiae) and expressed as fusion proteins with glutathione (S)-transferase were tested for their ability to reduce three homologous cyclic β-keto esters. The majority of dehydrogenases reduced ethyl 2-oxo-cyclopentanecarboxylate, yielding a pair of diastereomeric alcohols with consistent (1R)-stereochemistry. Ethyl 2-oxo-cyclohexanecarboxylate reductions afforded only cis-alcohol enantiomers. Ethyl 2-oxo-cycloheptanecarboxylate was accepted by two enzymes in the collection, and both yielded mainly the cis-(1R,2S)-alcohol. Escherichia coli cells overexpressing the YDL124w gene were used in a dynamic kinetic resolution of ethyl 2-oxo-cyclohexanecarboxylate to produce the key intermediate in a chemo-enzymatic synthesis of (1R,2S)-2-methyl-1-cyclohexanol, an important chiral building block.
A recombinant ketoreductase tool-box. Assessing the substrate selectivity and stereoselectivity toward the reduction of β-ketoesters
Zhu, Dunming,Mukherjee, Chandrani,Rozzell, J. David,Kambourakis, Spiros,Hua, Ling
, p. 901 - 905 (2007/10/03)
The substrate selectivity and stereoselectivity of a series of ketoreductases were evaluated toward the reduction of two sets of β-ketoesters. Both the structural variety at β-position and the substituent at α-position greatly affected the activity and stereoselectivity of these ketoreductases. For the first set of β-ketoesters, at least one ketoreductase was found that catalyzed the formation of either (d) or (l) enantiomer of β-hydroxyesters from each substrate with high optical purity, with the only exception of ethyl (d)-3-hydroxy-3-phenylpropionate. For the second set of β-ketoesters with α-substituents, the situation is more complex. More commonly, a ketoreductase was found that formed one of the four diastereomers in optically pure form, with only a few cases in which enzymes could be found that formed two or more of the diastereomers in high optical purity. The continued development of new, more diverse ketoreductases will create the capability to produce a wider range of single diastereomers of 2-substituted-3-hydroxy acids and their derivatives.
New efficient synthesis of Taniaphos ligands: Application in ruthenium- and rhodium-catalyzed enantioselective hydrogenations
Tappe, Katja,Knochel, Paul
, p. 91 - 102 (2007/10/03)
A third generation of Taniaphos 1,5-diphosphine ferrocene ligands with the new and interesting (SFc,3S)- and (RFc,3R)-configurations has been prepared. With these ligands, the ruthenium-catalyzed hydrogenation of C=O bonds proceeded with high diastereo- and enantioselectivity (up to >99% de and 97% ee). Good results were also obtained for the rhodium-catalyzed hydrogenation of C=C (up to 96% ee) and C=N bonds (up to 65% ee).
Lipase-catalysed resolution of cyclic cis- and trans-β-hydroxy esters
Levy, Laura M.,Dehli, Juan R.,Gotor, Vicente
, p. 2053 - 2058 (2007/10/03)
Lipases A and B from Candida antarctica are shown to be highly efficient and complementary biocatalysts for the resolution of five- to seven-membered cyclic β-hydroxy esters by O-acylation. Using this procedure, all four stereoisomers of each one are obtained in enantiopure form and very high yields.
Synthesis of a new class of chiral 1,5-diphosphanylferrocene ligands and their use in enantioselective hydrogenation
Ireland, Tania,Tappe, Katja,Grossheimann, Gabi,Knochel, Paul
, p. 843 - 852 (2007/10/03)
A new family of ferrocenylphosphane ligands has been prepared. Their flexible synthesis allows many structural modifications. The asymmetric induction of these ligands was examined in the hydrogenation of functionalized C=C, C=O, and C=N bonds. The enantioselectivity of the reaction was strongly dependent on the substituent R at the position α to the ferrocene moiety. In many cases, both enantiomeric β-hydroxyesters of the reduction product can be obtained by simply replacing a dimethylamino group in the ligand with a methyl group.
