@article { ISI:000236419800016, title = {MCM-41-supported platinum carbonyl cluster-derived catalysts for asymmetric and nonasymmetric hydrogenation reactions}, journal = {Journal of Catalysis}, volume = {239}, number = {1}, year = {2006}, month = {APR}, pages = {154-161}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Anionic platinum carbonyl Cluster ([Pt-12(CO)(24)](2-)) was ion-paired with the 3-chloropropyltrimethoxysilyl-ammonium group chemically bound to the surface of MCM-41. The materials undergo quick decarbonylation and have been characterized before decarbonylation by IR and UV-vis spectroscopy and after decarbonylation by XPS and TEM. They have been used as catalysts for the hydrogenations of methyl pyruvate, acetophenone, nitrobenzene, benzonitrile, and ethylacetoacetate. The support and the quaternary ammonium groups have significant effects on surface platinum concentration, crystallite size, and observed activity. In the hydrogenation of the prochiral substrates methyl pyruvate or acetophenone, the cinchonidine-based catalyst gives significant enantioselectivity under optimum conditions. A kinetic model that includes an enantioselective product-formation step and a hydrogen pressure-dependent step for the deactivation of the enantioselective sites gives reasonable agreement between predicted and observed enantioselectivity. The model is also in accordance with the XPS and TEM data. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {asymmetric/non-asymmetric catalysis, Enantioselectivity, functionalized MCM-41, hydrogenation catalysts, platinum carbonyl cluster}, issn = {0021-9517}, doi = {10.1016/j.jcat.2006.01.032}, author = {Basu, Susmit and Mapa, Maitri and Gopinath, Chinnakonda S. and Doble, Mukesh and Bhaduri, Sumit and Lahiri, Goutam Kumar} } @article { ISI:000254798300018, title = {Lipases catalyzed enantioselective hydrolysis of (R,S)-methyl 1,4-benzodioxan-2-carboxylate intermediate for (S)-doxazosin mesylate}, journal = {World Journal of Microbiology \& Biotechnology}, volume = {24}, number = {4}, year = {2008}, month = {APR}, pages = {577-579}, publisher = {SPRINGER}, address = {233 SPRING STREET, NEW YORK, NY 10013 USA}, abstract = {

(S)-1,4-benzodioxan-2-carboxylic acid-1 is used as starting compound for the production of the more effective (S) enantiomer of the drug doxazosin mesylate. The catalytic ability of some commercial lipases for preparations of (S) enantiomer of 1 from (+/-) methyl 1,4-benzodioxin-2-carboxylate-2 is reported. Lipases from bacterial sources were more successful in resolving the ester than those from the yeast lipases. About 85\% enantiomerically pure ester was achieved by lipase from alcaligenes sp.

}, keywords = {1, 4-benzodioxan-2-carboxylate, 4-benzodioxan-2-carboxylic acid, doxazosin, Enantioselectivity, Lipases}, issn = {0959-3993}, doi = {10.1007/s11274-007-9504-6}, author = {Varma, Rita and Kasture, Sangita M. and Nene, Sanjay and Kalkote, Uttam R.} } @article { ISI:000261909800003, title = {Arthrobacter sp lipase immobilization for preparation of enantiopure masked beta-amino alcohols}, journal = {Bioorganic \& Medicinal Chemistry}, volume = {17}, number = {1}, year = {2009}, month = {JAN}, pages = {29-34}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Recent reports on immobilization of lipase from Arthrobacter sp. (ABL, MTCC 5125; IIIM isolate) on insoluble polymers have shown altered properties including stability and enantioselectivity. Present work demonstrates a facile method for the preparation of enantiopure beta-amino alcohols by modulation of ABL enzyme properties via immobilization on insoluble as well as soluble supports using entrapment/covalent binding techniques. Efficacies of immobilized ABL on insoluble supports prepared from tetraethylorthosilicate/aminopropyltriethoxy silane and soluble supports derived from copolymerization of N-vinyl pyrrolidone-allylglycidyl ether (ANP type)/N-vinyl pyrrolidone-glycidyl methacrylate ( GNP type) for kinetic resolution of masked beta-amino alcohols have been studied vis-a-vis free ABL enzyme/wet cell biomass. The immobilized lipase on different insoluble/soluble supports has shown 21 - 110 mg/g protein binding and 30 - 700 U/g activity for hydrolyzing tributyrin substrate. The findings have shown a significant enhancement in enantioselectivity (ee 99\%) vis-a-vis wet cell biomass providing ee 70-90\% for resolution of beta-amino alcohols. (c) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {Arthrobacter sp lipase, beta-Aminoalcohol, Enantioselectivity, Immobilization, soluble polymer}, issn = {0968-0896}, doi = {10.1016/j.bmc.2008.11.023}, author = {Chaubey, Asha and Parshad, Rajinder and Gupta, Pankaj and Taneja, Subhash C. and Qazi, Ghulam N. and Rajan, C. R. and Ponrathnam, S.} } @article { ISI:000279746300009, title = {Enantioselective synthesis of (+)-alpha-conhydrine and (-)-sedamine by L-proline-catalysed alpha-aminooxylation}, journal = {European Journal of Organic Chemistry}, number = {18}, year = {2010}, month = {JUN}, pages = {3437-3444}, publisher = {WILEY-BLACKWELL}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

An efficient organocatalytic approach to the enantioslective synthesis of two important piperidine alkaloids, namely (+)-alpha-conhydrine (98\% ee) and (-)-sedamine (95\% ee), by L-proline-catalysed alpha-aminooxylation of aldehydes has been developed. The strategy involves an intramolecular cyclization to construct the piperidine core.

}, keywords = {alkaloids, Amino acids, Aminooxylation, Enantioselectivity, organocatalysis}, issn = {1434-193X}, doi = {10.1002/ejoc.201000169}, author = {Shaikh, Tanveer Mahamadali and Sudalai, Arumugam} } @article { ISI:000308878400007, title = {Immobilization of enantioselective lipase on soluble supports for kinetic resolution of drug intermediates}, journal = {Journal of Bioactive and Compatible Polymers}, volume = {27}, number = {5}, year = {2012}, month = {SEP}, pages = {499-509}, publisher = {SAGE PUBLICATIONS LTD}, address = {1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND}, abstract = {

The microbial lipase, Arthrobacter sp. lipase (MTCC 5125), from the Indian Institute of Integrative Medicine repository, is known as an effective catalyst for high enantioselective kinetic resolution of drug intermediates. The ABL was immobilized on water-soluble linear supports by covalently binding it to the epoxy groups on the N-vinyl pyrrolidone/allyl glycidyl ether and N-vinyl pyrrolidone/glycidyl methacrylate copolymers. The immobilized lipase, on different soluble supports, had 90-110 mg/g protein binding and 500-700 U/g hydrolysis activities for tributyrin substrate. These copolymers had soluble/insoluble characteristics in different pH ranges, which is an advantage over insoluble copolymers. A soluble polymer at neutral pH provided better accessibility to the immobilized enzyme, which was recovered by precipitation at pH 2-3 for reuse. Kinetic resolution of racemic acyl derivatives of chiral auxiliaries and drug intermediates, namely, phenyl ethanol, aminoalcohol, and fluoxetine intermediate resulted in a significant enhancement in enantioselectivity (99\%).

}, keywords = {Arthrobacter sp lipase, Enantioselectivity, Immobilization, Kinetic resolution, N-vinylpyrrolidone, soluble polymer}, issn = {0883-9115}, doi = {10.1177/0883911512453638}, author = {Chaubey, Asha and Parshad, Rajinder and Taneja, Subhash C. and Deokar, Sarika Babasaheb and Raman, Rajan C. and Ponrathnam, Surendra} } @article { ISI:000335152300007, title = {Croncise organocatalytic route to protected (2S, 4R)-4-hydroxyornithine and(+)-pseudohygroline}, journal = {Synlett}, volume = {25}, number = {8}, year = {2014}, month = {MAY}, pages = {1089-1092}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A practical, efficient, and organocatalytic approach to the synthesis of (2S,4R)-4-hydroxyornithine and (+)-pseudohygroline is reported using proline-catalyzed sequential alpha-aminoxylation/alpha-amination reaction and Horner-Wadsworth-Emmons olefination reaction of an aldehyde as the key step.

}, keywords = {aldehydes, Amination, Amino alcohols, cyclization, Enantioselectivity, Wittig reaction}, issn = {0936-5214}, doi = {10.1055/s-0033-1340977}, author = {Jha, Vishwajeet and Kumar, Pradeep} } @article { ISI:000354982900007, title = {Concise enantioselective synthesis of naturally active (S)-3-hydroxypiperidine}, journal = {Synthetic Communications}, volume = {45}, number = {13}, year = {2015}, month = {APR}, pages = {1559-1565}, publisher = {TAYLOR \& FRANCIS INC}, address = {530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA}, abstract = {

A short and efficient enantioselective synthesis of natural product (S)-3-hydroxypiperidine has been achieved starting from commercially available raw materials employing two catalytic routes: (i) cocatalyzed hydrolytic kinetic resolution (HKR) of racemic methyl-3-(oxiran-2-yl)propanoate; (ii) proline-catalyzed -aminooxylation followed by Horner-Wardsworth-Emmons olefination in high enantiomeric purity (97\% ee) and high overall yield (38\%).

}, keywords = {Asymmetric synthesis, bioactivity, Enantioselectivity, Natural products, organocatalysis}, issn = {0039-7911}, doi = {10.1080/00397911.2015.1033428}, author = {Dey, Soumen and Karabal, Pratibha U. and Sudalai, Arumugam} } @article { ISI:000364968800017, title = {First enantioselective synthesis of surinamensinol B and a non-natural polysphorin analogue by a two-stereocentered hydrolytic kinetic resolution}, journal = {European Journal of Organic Chemistry}, volume = {33}, number = {33}, year = {2015}, month = {NOV}, pages = {7344-7351}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

An efficient and economical approach to the synthesis of antitumor and anti-inflammatory surinamensinol B (1) and antimalarial polysphorin analogue 2 has been achieved with high enantiomeric purity (96\% ee) by starting from commercially available 3,4,5-trimethoxybenzaldehyde. The key steps of the strategy include a Co-catalyzed two-stereocentered hydrolytic kinetic resolution (HKR) of racemic 2[( methoxymethoxy)(3,4,5-trimethoxyphenyl)methyl] oxirane (13) as the chiral inducing step followed by a Mitsunobu reaction. Chiral epoxide 14 and chiral diol 15 were utilized in the syntheses of both compounds.

}, keywords = {Biological activity, Enantioselectivity, Kinetic resolution, Natural products, Total synthesis}, issn = {1434-193X}, doi = {10.1002/ejoc.201501009}, author = {Lalwani, Komal G. and Sudalai, Arumugam} } @article { ISI:000350056800015, title = {Proline-catalyzed alpha-aminooxylation of beta-amino aldehydes: access to enantiomerically pure syn- and anti-3-amino-3-aryl-1,2-alkanediols}, journal = {Synlett}, volume = {26}, number = {3}, year = {2015}, month = {FEB}, pages = {355-358}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A new synthetic method for enantioselective synthesis of syn 3-amino-3-aryl-1,2-alkanediols via praline catalyzed alpha-aminaoxn y ylation of beta-amino aldehydes des are described. This methodology is successfully applied to a concise and protecting group-free asymmetric synthesis of (-)-cytoxazone (+)-epi-cytoxazone and formal synthesis of N-thiolated 2-oxazolidinone.

}, keywords = {amino aldehydes, Asymmetric synthesis, catalysis, diastereoselectivity, Enantioselectivity, Natural product}, issn = {0936-5214}, doi = {10.1055/s-0034-1379735}, author = {Venkataramasubramanian, V. and Kiran, I. N. Chaithanya and Sudalai, Arumugam} } @article { ISI:000350116200014, title = {Robustness screen in enantioselective catalysis enabled generation of enantioenriched heterocyclic scaffolds in one pot}, journal = {Chemistry-A European Journal}, volume = {21}, number = {9}, year = {2015}, month = {FEB}, pages = {3580-3584}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Enantioselective catalysis has emerged as a powerful synthetic paradigm and has accelerated the development of new methods to make diverse chiral molecules. Generally, these reactions are very sensitive to the steric and electronic environment present in the catalyst as well as the substrates. With this scenario, the presence of an additional component in the reaction mixture is expected to add complexity in achieving the enantioselective variants. Herein, we report that various enantioenriched molecules could be obtained from multiple starting materials in one pot. The reaction of aminoaromatics A with alkynols B-1, B-2, B-3...B-n with a Au-I/chiral BrOnsted acid catalyst afforded AB(1)*, AB(2)*, AB(3)*...AB(n)*; while, the reaction of alkynols B with aminoaromatics A(1), A(2), A(3)...A(n) under the same reaction conditions gave A(1)B*, A(2)B*, A(3)B*...A(n)B*.

}, keywords = {chiral Bronsted acid, Enantioselectivity, Gold, molecular scaffolds, robustness screen}, issn = {0947-6539}, doi = {10.1002/chem.201406045}, author = {Bagle, Pradip N. and Shinde, Valmik S. and Patil, Nitin T.} } @article {45473, title = {Organocatalytic asymmetric cascade reaction of gamma-substituted deconjugated butenolides with o-formyl-beta-nitrostyrene}, journal = {ChemistrySelect}, volume = {3}, year = {2018}, month = {JUL}, pages = {8189-8192}, type = {Article}, abstract = {

An efficient chemo-, diastereo- and enantio-selective cascade synthesis of functionalized indanols bearing four contiguous stereogenic centres has been developed via the reaction of beta,gamma-butenolides with o-formyl-beta-nitrostyrenes in the presence of bi-functional hydrogen-bonding catalyst. Indanol derivatives containing gamma,gamma-disubstituted butenolides were obtained in good yields and with moderate to high enantioselectivities/diastereoselectivities.

}, keywords = {butenolides, Cascade reaction, Enantioselectivity, Indanol, organocatalysis}, issn = {2365-6549}, doi = {10.1002/slct.201801467}, author = {Deepake, Siddharth K. and Lanjewar, Atul B. and Thatikonda, Thanusha and Gonnade, Rajesh G. and Das, Utpal} } @article {46353, title = {Concise formal synthesis of (-)-(6R,11R,14R)-colletallol via D-proline catalysed alpha-aminooxylation-Wittig olefination strategy}, journal = {Indian Journal of Chemistry Section B-Organic Chemistry Including Medicinal Chemistry}, volume = {58}, year = {2019}, month = {SEP}, pages = {1029-1036}, type = {Article}, abstract = {

An efficient enantioselective formal synthesis of marine macrolide (-)-(6R,11R,14R)-colletallol has been achieved starting from commercially available raw materials. The key reactions include the D-proline catalyzed a-aminooxylation of aldehyde followed by Horner-Wardsworth-Emmons olefination in a sequential fashion to give the macrolide key intermediate 5 in high enantiomeric purity (97\% ee) and high overall yield (32\%).

}, keywords = {alpha-aminoxylation, Asymmetric synthesis, Enantioselectivity, Natural products, organocatalysis}, issn = {0376-4699}, author = {Dey, Soumen and Gadakh, Sunita and Sudalai, Arumugam} } @article {48714, title = {"Weak" C-H{\textbullet}{\textbullet}{\textbullet}S interaction drives enantioselectivity in cinchona alkaloid complex catalyzed thiocyanation}, journal = {Chemistry-An Asian Journal}, volume = {18}, year = {2023}, month = {JUL}, pages = {e202300321}, type = {Article}, abstract = {

The great success of asymmetric organocatalysis has made it one of the most important advancements made in chemistry in the past two decades. A significant achievement in this context is the asymmetric organocatalysis of the thiocyanation reaction. In the current study, computational studies with density functional theory have been done in order to understand an interesting experimental finding: the reversal of enantioselectivity from R to S when the electrophile is changed from beta-keto ester to oxindole for the thiocyanation reaction with the cinchona alkaloid complex catalyst. The calculations reveal an unusual fact - the principal reason for the reversal is the presence of the C-H center dot center dot center dot S noncovalent interaction, which is present only in the major transition states in each of the two nucleophile cases. Only recently has it been realized that the supposedly weak C-H center dot center dot center dot S noncovalent interaction has the properties of a hydrogen bond, and the fact that this interaction is the cause of enantioselectivity has relevance, because of the large number of asymmetric transformations involving the sulphur heteroatom.

}, keywords = {Density functional calculations, Enantioselectivity, noncovalent interactions, organocatalysis, reaction mechanisms}, issn = {1861-4728}, doi = {10.1002/asia.202300321}, author = {Banerjee, Subhrashis and Vanka, Kumar} }