158807-51-3Relevant academic research and scientific papers
Studies on N-activation for the lipase-catalyzed enantioselective preparation of β-amino esters from 4-phenylazetidin-2-one
Sundell, Riku,Kanerva, Liisa T.
, p. 1500 - 1506 (2015/03/04)
The effect of N-substitution was examined for the enantio-selective lipase-catalyzed ring-opening reaction of racemic 4-phenylazetidin-2-one with methanol in dry organic solvents. Marked differences in the reactivity of various N-protected 4-phenylazetidin-2-ones were observed. Preparativescale reactions with Candida antarctica lipase B (Novozym 435 preparation) yielded N-acylated methyl (R)-3-amino-3- phenylpropanoates with enantiomeric excess (ee) values >99% in up to a 49% isolated yield, whereas Thermomyces lanuginosus lipase (Lipozyme TM IM) gave enantiomerically enriched methyl (S)-3-acetamido-3-phenylpropanoate. Candida antarctica lipase A catalyzed the cleavage of the N-chloroacetyl protective group, whereas all of the other examined lipases underwent the ring-opening reaction.
Carica papaya lipase catalysed resolution of β-amino esters for the highly enantioselective synthesis of (S)-dapoxetine
You, Pengyong,Qiu, Jian,Su, Erzheng,Wei, Dongzhi
, p. 557 - 565 (2013/03/13)
An efficient synthesis of the (S)-3-amino-3-phenylpropanoic acid enantiomer has been achieved by Carica papaya lipase (CPL) catalysed enantioselective alcoholysis of the corresponding racemic N-protected 2,2,2-trifluoroethyl esters in an organic solvent. A high enantioselectivity (E > 200) was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. Based on the resolution of a series of amino acids, it was found that the structure of the substrate has a profound effect on the CPL-catalysed resolution. The enantioselectivity and reaction rate were significantly enhanced by switching the conventional methyl ester to an activated trifluoroethyl ester. When considering steric effects, the substituted phenyl and amino groups should not both be large for the CPL-catalysed resolution. The mechanism of the CPL-catalysed enantioselective alcoholoysis of the amino acids is discussed to delineate the substrate requirements for CPL-catalysed resolution. Finally, the reaction was scaled up, and the products were separated and obtained in good yields (≥ 80 %). The (S)-3-amino-3- phenylpropanoic acid obtained was used as a key chiral intermediate in the synthesis of (S)-dapoxetine with very high enantiomeric excess (> 99 %). A carica papaya lipase catalysed resolution of N-protected β-phenylalanine esters has been developed. High enantioselectivity was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. After 50 % conversion, the products were separated and used as key chiral intermediates for the synthesis of (S)-dapoxetine with > 99 % ee. Copyright
Disulfonimide-catalyzed asymmetric synthesis of β3-amino esters directly from N-Boc-amino sulfones
Wang, Qinggang,Leutzsch, Markus,Van Gemmeren, Manuel,List, Benjamin
, p. 15334 - 15337 (2013/11/06)
An asymmetric Mannich reaction of silyl ketene acetals with N-Boc-amino sulfones has been developed. A chiral disulfonimide efficiently catalyzes both the in situ generation of the corresponding N-Boc imines and the asymmetric Mannich reaction with excellent yields and enantioselectivities. Kinetic studies confirm a proposed stepwise mechanism.
COMPLEMENT PATHWAY MODULATORS AND USES THEREOF
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Page/Page column 95; 100, (2014/01/09)
The present invention provides a compound of formula I a method for manufacturing the compounds of the invention, and its therapeutic uses as inhibitor of the complement alternative pathway and particularly as inhibitor of Factor B for the treatment of e.g. age-related macular degeneration and diabetic retinopathy. The present invention further provides a combination of pharmacologically active agents and a pharmaceutical composition.
Fluorinated β2- and β3-amino acids: Synthesis and inhibition of α-chymotrypsin
Peddie, Victoria,Pietsch, Markus,Bromfield, Karen M.,Pike, Robert N.,Duggan, Peter J.,Abell, Andrew D.
experimental part, p. 1845 - 1859 (2010/10/18)
The synthesis of a series of -fluorinated β2- and β3-amino acid derivatives is described. Stereoselective fluorination at the -carbon of the β3-amino acids was achieved by deprotonation with lithium diisopropylamide followed by treatment with N-fluorobenzenesulfonimide. Fluorination of β2-amino acids employed the chiral auxiliary (4R)-4-benzyl-2-oxazolidinone. The α-fluorinated amino acids and their non-fluorinated precursors were found to competitively inhibit α-chymotrypsin. Georg Thieme Verlag Stuttgart New York.
Oxazinanones as chiral auxiliaries: Synthesis and evaluation in enolate alkylations and aldol reactions
Davies, Stephen G.,Garner, A. Christopher,Roberts, Paul M.,Smith, Andrew D.,Sweet, Miles J.,Thomson, James E.
, p. 2753 - 2768 (2008/02/10)
Homochiral β-amino esters (prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-Acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one than the corresponding Evans oxazolidin-2-one. A C(4)-iso-propyl stereodirecting group within the oxazinanone conveys higher stereoselectivity than the analogous C(4)-phenyl substituent. gem-Dimethyl substitution at C(6) within the oxazinanone framework facilitates exclusive exocyclic cleavage upon hydrolysis to furnish α-substituted carboxylic acid derivatives and the parent oxazinanone in good yield. Asymmetric aldol reactions of a range of aromatic and aliphatic aldehydes with the chlorotitanium enolate of (R)-N-propanoyl-4-iso- propyl-6,6-dimethyl-oxazinan-2-one proceed with excellent diastereoselectivity. Hydrolysis of the aldol products affords homochiral α-methyl-β- hydroxy-carboxylic acids. The Royal Society of Chemistry 2006.
Direct enantio- and diastereoselective Mannich reactions of malonate and β-keto esters with N-Boc and N-Cbz aldimines catalysed by a bifunctional cinchonine derivative
Tillman, A. Louise,Ye, Jinxing,Dixon, Darren J.
, p. 1191 - 1193 (2008/02/03)
A highly enantioselective Mannich reaction between malonate esters and N-Boc and N-Cbz aldimines, catalysed by a bifunctional cinchonine derivative, has been developed; extension of this methodology to encompass the use of 2-substituted-1,3-dicarbonyl nuc
Enzymatic resolution of N-protected-β3-amino methyl esters, using lipase B from Candida antarctica
Flores-Sanchez, Patricia,Escalante, Jaime,Castillo, Edmundo
, p. 629 - 634 (2007/10/03)
Racemic β3-amino methyl esters bearing the amine function protected with Bz, Cbz, Boc, Fmoc and as aminobenzamide, were resolved by enantiospecific transesterifications catalyzed by lipase B from Candida antarctica. The reactions proceeded with
Asymmetric catalytic Mannich reactions catalyzed by urea derivatives: Enantioselective synthesis of β-aryl-β-amino acids
Wenzel, Anna G.,Jacobsen, Eric N.
, p. 12964 - 12965 (2007/10/03)
Highly enantioselective addition reactions between silyl ketene acetals and N-Boc aldimines are catalyzed by the thiourea-based catalyst 1c. Extraordinary scope is observed in this methodology with regard to the imine substrate, with aryl and heteroaromatic derivatives generally affording nearly quantitative yields of β-amino ester product in up to 98% enantioselectivity. Copyright
