Eusebio Juaristi - Academia.edu (original) (raw)
Papers by Eusebio Juaristi
Synthesis Stuttgart, 1995
Tetrahedron Letters, 1984
... 1 Eusebio Juaristi* and J. Daniel Reyna Departamento de QuImica del Centro de Investigacion y... more ... 1 Eusebio Juaristi* and J. Daniel Reyna Departamento de QuImica del Centro de Investigacion y de Estudios Avanzados del Instituto Po1itcnico Nacional, Apartado Postal 14740 ... Chem. Abstr., 19S9, 53, 1250 f. 7. For recent examples see: Sundberg, RJ; Laurino, JP, J. Org. ...
The Journal of Organic Chemistry, Mar 1, 2000
A variable-temperature NMR study of (cis-4-methylcyclohexyl)methyl sulfide (1), sulfoxide (2), an... more A variable-temperature NMR study of (cis-4-methylcyclohexyl)methyl sulfide (1), sulfoxide (2), and sulfone (3), as well as (cis-4-methylcyclohexyl)phenyl sulfide (4), sulfoxide (5), and sulfone (6) allowed determination of the thermodynamic parameters, DeltaH degrees and DeltaS degrees, for the title groups. Reproduction of the experimental results with Allinger's MM3 program was successfully accomplished in the case of the sulfoxide and sulfide groups. Nevertheless, modification of the original force field torsional parameters was required in order to adequately reproduce the experimentally observed behavior of the sulfonyl derivatives. Rationalization of the enthalpic and entropic contributions to DeltaG degrees [S(O)(n)()R, n = 0, 1, 2; R = CH(3), Ph] is advanced in terms of the steric characteristics of these sulfur-containing groups and the resulting rotameric populations in the axial and equatorial monosubstituted cyclohexanes.
The Journal of Organic Chemistry, Nov 5, 2010
The reactivity of N-tert-butyloxycarbonyl-N-carboxyanhydrides derived from β-alanine, (S)-β(3)-ho... more The reactivity of N-tert-butyloxycarbonyl-N-carboxyanhydrides derived from β-alanine, (S)-β(3)-homophenylglycine, and (S)-β(3)-carboxyhomoglycine with different α- and β-amino ester hydrochlorides was examined under ball-milling activation. In particular, good to excellent yields of several relevant α,β- and β,β-dipeptides were obtained. An illustrative application of this methodology consisted in the high-yield synthesis of the mammalian α,β-dipeptide N-Boc-l-carnosine-OMe.
J Org Chem, 1988
Eusebio Juaristi* and J. Samuel Cruz-SBnchez Departamento de Quimica, Centro de Investigacidn y d... more Eusebio Juaristi* and J. Samuel Cruz-SBnchez Departamento de Quimica, Centro de Investigacidn y de Estudios Auanzados del IPN, Apdo. Postal 14-740, 07000 MGwico D F., Mexico Received January 25, 1988 ... The synthesis of the title compound (6), an interesting subject for the ...
J Am Chem Soc, 1993
The conformational energy of the trimethylphosphonium group in the 1,3-dithian-2-yl system was de... more The conformational energy of the trimethylphosphonium group in the 1,3-dithian-2-yl system was determined by multinuclear ('H, I3C, 31P) NMR analysis of the mobile title compound as well as the corresponding conformationally fixed models. A definite preference for the axial conformation, = 0.36 f 0.10 kcal/mol, reflects a substantial S-C-+PMe, anomeric effect in this system, with a value at least equal to 2.2 kcal/mol. This result is compared with thermodynamic data obtained from the systematic study of other 2-P-substituted 1,3-dithianes, in order to gain insight into the nature of the SX-P anomeric effect. In particular, the trimethylphosphonium group lacks unshared electrons; therefore, this result is not in line with interpretations of the S-C-P anomeric effect invoking a dominant repulsion between electrons at sulfur and the P-substituents in the equatorial conformation. Analysis of the NMR spectroscopic data lends support to a tweelectron/tweorbital stereoelectronic interaction that stabilizes the axial isomer. Furthermore, the substantial anomeric effect observed in the title system clearly violates expectations in terms of the so-called *reverse anomeric effect". (8) See, for example: (a) Mikolajczyk, M. Pure Appl. Chem. 1987, 59, 983. (b) Pinto, B. M.; Johnson, B. D.; Sandoval-Ramirez, J.; Sharma, R. D. (10) Mikolajczyk, M.; Gracyk, P.; Kabachnik, M. I.; Baranov, A. P. J . Org. Chem. 1989, 54, 2859. (1 1) A recent review article favors this hypothesis: Zamojski, A. Chemtracts: Org. Chem. 1990, 3. 396. Chem., I n f . Ed. Engl. 1991, 30, 578. ( I 2) Mikolajczyk. M.; Gracyk, P.; Wieczorek, M. W.; Bujacz, G. Angew.
Tetrahedron, Mar 20, 1995
The preparation of four new stereoisomeric 1-carbobenzyloxy-2-tert-butyl-3-(α-methylbenzyl)-1,3-i... more The preparation of four new stereoisomeric 1-carbobenzyloxy-2-tert-butyl-3-(α-methylbenzyl)-1,3-imidazolidin-4-ones is described. Alkylation of the lithium enolates of these chiral glycine derivatives proceeds with high diastereoselectivity. In particular, the reaction of the unlike isomers, (2R, 1′S)- and (2S, 1′R)-7, afforded the desired phosphorylated products 9 with ≥ 98% diastereoselectivity. Hydrolysis of the alkylated products proceeds under relatively mild conditions to give enantiomerically pure
Tetrahedron Asymmetry, 1997
A high-yield, five-step synthesis of novel enantiomerically pure cis- and trans-N-(propionyl)-hex... more A high-yield, five-step synthesis of novel enantiomerically pure cis- and trans-N-(propionyl)-hexahydrobenzoxazolidin-2-ones5a-d from cyclohexene oxide and (S)-α-methylbenzylamine is described. The highly diastereoselective benzylation of 5b is also described.
J Org Chem, 1984
The reaction of 2-phenyl-l, 3-dithianyllithium (1-Li) with 4-tert-butylcyclohexanone in cyclohexa... more The reaction of 2-phenyl-l, 3-dithianyllithium (1-Li) with 4-tert-butylcyclohexanone in cyclohexane and tetrahydrofuran may proceed either with kinetic or thermodynamic control. In the latter case carbinol formation involves exclusively equatorial attack. In contrast, only ...
Helvetica Chimica Acta, Feb 4, 1987
Introduction. - In addition to their fundamental biochemical and physiological signif-icance6), a... more Introduction. - In addition to their fundamental biochemical and physiological signif-icance6), amino acids are important in human and animal nutrition and as flavorings, taste enhancers, and sweeteners [l]. Both natural7) and unnatural amino acids are also ...
Cheminform, Nov 9, 2010
AbstractEnantiopure carbonates undergo the amination with complete retention of the configuration.
Tetrahedron, Jul 3, 2010
A pratical, highly enantioselective method for the synthesis of dehydro-b-amino acids was develop... more A pratical, highly enantioselective method for the synthesis of dehydro-b-amino acids was developed starting from easily accessible enantiopure allylic carbonates. The substitution with amines for CeN bond formation on these substrates bearing substituents on the Ca, Cb, and Cg position of the allylic system has received, until now, little attention. The reactions, carried out under palladium-catalyzed conditions, resulted in good yields and complete regioselectivity. Moreover, starting from enantiopure carbonates, complete retention of the configuration could be observed, affording enantiopure allylic amines.
Journal of Organic Chemistry, 2007
Nineteen chiral amines and their derivatives were prepared and investigated as organocatalytic Le... more Nineteen chiral amines and their derivatives were prepared and investigated as organocatalytic Lewis bases in the R-amination of ethyl R-phenyl-R-cyanoacetate. For comparison purposes, a few natural products were also examined as catalysts in this study. Among the results obtained, (R)-N-benzyl-N-(1-phenylethyl)-amine and (R,R)-N,N′-bis(1-phenylethyl)-propane-1,3-diamine as the catalysts afforded the amination products in excellent yields and with up to 84% ee. By contrast, under comparable conditions the two derivatives of natural products (DHQ) 2 PYR and (DHQD) 2 PYR provided the product of amination with lower than 10% enantiomeric excess.
Tetrahedron, 1999
The conformational behavior of 2-substituted 1,3-dithianes 1-3 (Y = SC6H5, CO2Et, COC6H5) was stu... more The conformational behavior of 2-substituted 1,3-dithianes 1-3 (Y = SC6H5, CO2Et, COC6H5) was studied by 13C NMR spectroscopy in the 228-318 K temperature range. Plots of In K versus l/T are linear, permitting evaluation of the enthalpic and entropic contributions to the S-C-Y anomeric effects in these heterocycles. Ab initio Density Functional Theory calculations in the gas phase and in solution were carried out on slightly simplified models with Y = SCH3, CO2CH3, and COCH3. The influence of the solvent was simulated with a self-consistent reaction field (SCRF) continuum model. The axial preference observed for 1-3 is reproduced by calculation.
Tetrahedron Lett, 2011
The efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (2S)-isopropyl-5-iodo... more The efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-one with, arylethynyl-, heteroarylethynyl-, and alkylethynyltrifluoroborate salts is reported. The standard protocol was evaluated and optimized in order to gain access to suitable precursors of enantiopure 2-substituted β-amino acids. The scope and limitations of this methodology are discussed.
Tetrahedron, Sep 1, 2011
The organocatalytic activity of (S)-proline-based dipeptides 1aec has been evaluated in the asymm... more The organocatalytic activity of (S)-proline-based dipeptides 1aec has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions in a ball mill. In particular, the methyl ester of (S)-proline-(S)-tryptophan, (S,S)-1c, proved to be an efficient organocatalyst, and the aldol reaction proceeded with good chemical yields and excellent diastereo-and enantioselectivity (up to 98:2 anti/syn dr and up to 98% ee), in the presence of water, and 5 mol % of benzoic acid as additive.
Pure Appl Chem, 2005
The cyclization of various β-amino acids with PhP(O)Cl 2 affords cyclo-β-dipeptides, whose boat c... more The cyclization of various β-amino acids with PhP(O)Cl 2 affords cyclo-β-dipeptides, whose boat conformation is probably responsible for the high diastereoselectivity observed in the alkylation reactions of their lithium enolate derivatives.
Educacion Quimica, Mar 31, 2013
Synthesis Stuttgart, 1995
Tetrahedron Letters, 1984
... 1 Eusebio Juaristi* and J. Daniel Reyna Departamento de QuImica del Centro de Investigacion y... more ... 1 Eusebio Juaristi* and J. Daniel Reyna Departamento de QuImica del Centro de Investigacion y de Estudios Avanzados del Instituto Po1itcnico Nacional, Apartado Postal 14740 ... Chem. Abstr., 19S9, 53, 1250 f. 7. For recent examples see: Sundberg, RJ; Laurino, JP, J. Org. ...
The Journal of Organic Chemistry, Mar 1, 2000
A variable-temperature NMR study of (cis-4-methylcyclohexyl)methyl sulfide (1), sulfoxide (2), an... more A variable-temperature NMR study of (cis-4-methylcyclohexyl)methyl sulfide (1), sulfoxide (2), and sulfone (3), as well as (cis-4-methylcyclohexyl)phenyl sulfide (4), sulfoxide (5), and sulfone (6) allowed determination of the thermodynamic parameters, DeltaH degrees and DeltaS degrees, for the title groups. Reproduction of the experimental results with Allinger's MM3 program was successfully accomplished in the case of the sulfoxide and sulfide groups. Nevertheless, modification of the original force field torsional parameters was required in order to adequately reproduce the experimentally observed behavior of the sulfonyl derivatives. Rationalization of the enthalpic and entropic contributions to DeltaG degrees [S(O)(n)()R, n = 0, 1, 2; R = CH(3), Ph] is advanced in terms of the steric characteristics of these sulfur-containing groups and the resulting rotameric populations in the axial and equatorial monosubstituted cyclohexanes.
The Journal of Organic Chemistry, Nov 5, 2010
The reactivity of N-tert-butyloxycarbonyl-N-carboxyanhydrides derived from β-alanine, (S)-β(3)-ho... more The reactivity of N-tert-butyloxycarbonyl-N-carboxyanhydrides derived from β-alanine, (S)-β(3)-homophenylglycine, and (S)-β(3)-carboxyhomoglycine with different α- and β-amino ester hydrochlorides was examined under ball-milling activation. In particular, good to excellent yields of several relevant α,β- and β,β-dipeptides were obtained. An illustrative application of this methodology consisted in the high-yield synthesis of the mammalian α,β-dipeptide N-Boc-l-carnosine-OMe.
J Org Chem, 1988
Eusebio Juaristi* and J. Samuel Cruz-SBnchez Departamento de Quimica, Centro de Investigacidn y d... more Eusebio Juaristi* and J. Samuel Cruz-SBnchez Departamento de Quimica, Centro de Investigacidn y de Estudios Auanzados del IPN, Apdo. Postal 14-740, 07000 MGwico D F., Mexico Received January 25, 1988 ... The synthesis of the title compound (6), an interesting subject for the ...
J Am Chem Soc, 1993
The conformational energy of the trimethylphosphonium group in the 1,3-dithian-2-yl system was de... more The conformational energy of the trimethylphosphonium group in the 1,3-dithian-2-yl system was determined by multinuclear ('H, I3C, 31P) NMR analysis of the mobile title compound as well as the corresponding conformationally fixed models. A definite preference for the axial conformation, = 0.36 f 0.10 kcal/mol, reflects a substantial S-C-+PMe, anomeric effect in this system, with a value at least equal to 2.2 kcal/mol. This result is compared with thermodynamic data obtained from the systematic study of other 2-P-substituted 1,3-dithianes, in order to gain insight into the nature of the SX-P anomeric effect. In particular, the trimethylphosphonium group lacks unshared electrons; therefore, this result is not in line with interpretations of the S-C-P anomeric effect invoking a dominant repulsion between electrons at sulfur and the P-substituents in the equatorial conformation. Analysis of the NMR spectroscopic data lends support to a tweelectron/tweorbital stereoelectronic interaction that stabilizes the axial isomer. Furthermore, the substantial anomeric effect observed in the title system clearly violates expectations in terms of the so-called *reverse anomeric effect". (8) See, for example: (a) Mikolajczyk, M. Pure Appl. Chem. 1987, 59, 983. (b) Pinto, B. M.; Johnson, B. D.; Sandoval-Ramirez, J.; Sharma, R. D. (10) Mikolajczyk, M.; Gracyk, P.; Kabachnik, M. I.; Baranov, A. P. J . Org. Chem. 1989, 54, 2859. (1 1) A recent review article favors this hypothesis: Zamojski, A. Chemtracts: Org. Chem. 1990, 3. 396. Chem., I n f . Ed. Engl. 1991, 30, 578. ( I 2) Mikolajczyk. M.; Gracyk, P.; Wieczorek, M. W.; Bujacz, G. Angew.
Tetrahedron, Mar 20, 1995
The preparation of four new stereoisomeric 1-carbobenzyloxy-2-tert-butyl-3-(α-methylbenzyl)-1,3-i... more The preparation of four new stereoisomeric 1-carbobenzyloxy-2-tert-butyl-3-(α-methylbenzyl)-1,3-imidazolidin-4-ones is described. Alkylation of the lithium enolates of these chiral glycine derivatives proceeds with high diastereoselectivity. In particular, the reaction of the unlike isomers, (2R, 1′S)- and (2S, 1′R)-7, afforded the desired phosphorylated products 9 with ≥ 98% diastereoselectivity. Hydrolysis of the alkylated products proceeds under relatively mild conditions to give enantiomerically pure
Tetrahedron Asymmetry, 1997
A high-yield, five-step synthesis of novel enantiomerically pure cis- and trans-N-(propionyl)-hex... more A high-yield, five-step synthesis of novel enantiomerically pure cis- and trans-N-(propionyl)-hexahydrobenzoxazolidin-2-ones5a-d from cyclohexene oxide and (S)-α-methylbenzylamine is described. The highly diastereoselective benzylation of 5b is also described.
J Org Chem, 1984
The reaction of 2-phenyl-l, 3-dithianyllithium (1-Li) with 4-tert-butylcyclohexanone in cyclohexa... more The reaction of 2-phenyl-l, 3-dithianyllithium (1-Li) with 4-tert-butylcyclohexanone in cyclohexane and tetrahydrofuran may proceed either with kinetic or thermodynamic control. In the latter case carbinol formation involves exclusively equatorial attack. In contrast, only ...
Helvetica Chimica Acta, Feb 4, 1987
Introduction. - In addition to their fundamental biochemical and physiological signif-icance6), a... more Introduction. - In addition to their fundamental biochemical and physiological signif-icance6), amino acids are important in human and animal nutrition and as flavorings, taste enhancers, and sweeteners [l]. Both natural7) and unnatural amino acids are also ...
Cheminform, Nov 9, 2010
AbstractEnantiopure carbonates undergo the amination with complete retention of the configuration.
Tetrahedron, Jul 3, 2010
A pratical, highly enantioselective method for the synthesis of dehydro-b-amino acids was develop... more A pratical, highly enantioselective method for the synthesis of dehydro-b-amino acids was developed starting from easily accessible enantiopure allylic carbonates. The substitution with amines for CeN bond formation on these substrates bearing substituents on the Ca, Cb, and Cg position of the allylic system has received, until now, little attention. The reactions, carried out under palladium-catalyzed conditions, resulted in good yields and complete regioselectivity. Moreover, starting from enantiopure carbonates, complete retention of the configuration could be observed, affording enantiopure allylic amines.
Journal of Organic Chemistry, 2007
Nineteen chiral amines and their derivatives were prepared and investigated as organocatalytic Le... more Nineteen chiral amines and their derivatives were prepared and investigated as organocatalytic Lewis bases in the R-amination of ethyl R-phenyl-R-cyanoacetate. For comparison purposes, a few natural products were also examined as catalysts in this study. Among the results obtained, (R)-N-benzyl-N-(1-phenylethyl)-amine and (R,R)-N,N′-bis(1-phenylethyl)-propane-1,3-diamine as the catalysts afforded the amination products in excellent yields and with up to 84% ee. By contrast, under comparable conditions the two derivatives of natural products (DHQ) 2 PYR and (DHQD) 2 PYR provided the product of amination with lower than 10% enantiomeric excess.
Tetrahedron, 1999
The conformational behavior of 2-substituted 1,3-dithianes 1-3 (Y = SC6H5, CO2Et, COC6H5) was stu... more The conformational behavior of 2-substituted 1,3-dithianes 1-3 (Y = SC6H5, CO2Et, COC6H5) was studied by 13C NMR spectroscopy in the 228-318 K temperature range. Plots of In K versus l/T are linear, permitting evaluation of the enthalpic and entropic contributions to the S-C-Y anomeric effects in these heterocycles. Ab initio Density Functional Theory calculations in the gas phase and in solution were carried out on slightly simplified models with Y = SCH3, CO2CH3, and COCH3. The influence of the solvent was simulated with a self-consistent reaction field (SCRF) continuum model. The axial preference observed for 1-3 is reproduced by calculation.
Tetrahedron Lett, 2011
The efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (2S)-isopropyl-5-iodo... more The efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of (2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-one with, arylethynyl-, heteroarylethynyl-, and alkylethynyltrifluoroborate salts is reported. The standard protocol was evaluated and optimized in order to gain access to suitable precursors of enantiopure 2-substituted β-amino acids. The scope and limitations of this methodology are discussed.
Tetrahedron, Sep 1, 2011
The organocatalytic activity of (S)-proline-based dipeptides 1aec has been evaluated in the asymm... more The organocatalytic activity of (S)-proline-based dipeptides 1aec has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions in a ball mill. In particular, the methyl ester of (S)-proline-(S)-tryptophan, (S,S)-1c, proved to be an efficient organocatalyst, and the aldol reaction proceeded with good chemical yields and excellent diastereo-and enantioselectivity (up to 98:2 anti/syn dr and up to 98% ee), in the presence of water, and 5 mol % of benzoic acid as additive.
Pure Appl Chem, 2005
The cyclization of various β-amino acids with PhP(O)Cl 2 affords cyclo-β-dipeptides, whose boat c... more The cyclization of various β-amino acids with PhP(O)Cl 2 affords cyclo-β-dipeptides, whose boat conformation is probably responsible for the high diastereoselectivity observed in the alkylation reactions of their lithium enolate derivatives.
Educacion Quimica, Mar 31, 2013