نتایج جستجو برای: stereoselectivity

تعداد نتایج: 1551  

Journal: :Journal of lipid research 2010
Danièle Lucas Sophie Goulitquer Jan Marienhagen Maude Fer Yvonne Dreano Ulrich Schwaneberg Yolande Amet Laurent Corcos

Cytochromes P450 (CYPs) metabolize polyunsaturated long-chain fatty acids (PUFA-LC) to several classes of oxygenated metabolites. Through use of human recombinant CYPs, we recently showed that CYP1A1, -2C19, -2D6, -2E1, and -3A4 are mainly hydroxylases, whereas CYP1A2, -2C8, -2C9, and -2J2 are mainly epoxygenases of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (D...

Journal: :Angewandte Chemie 2016
Priyanka Bajaj Gopeekrishnan Sreenilayam Vikas Tyagi Rudi Fasan

Engineered hemoproteins have recently emerged as promising systems for promoting asymmetric cyclopropanations, but variants featuring predictable, complementary stereoselectivity in these reactions have remained elusive. In this study, a rationally driven strategy was implemented and applied to engineer myoglobin variants capable of providing access to 1-carboxy-2-aryl-cyclopropanes with high t...

2016
Davide Brenna Elisabetta Massolo Alessandra Puglisi Sergio Rossi Giuseppe Celentano Maurizio Benaglia Vito Capriati

Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous synthesis of enantiomerically enriched products by testing different experimental set-ups. L-Proline-catalysed cross-aldol reactions were efficiently performed in continuo, with high yield (99%), anti-stereoselectivity, and enantioselectivity (up to 97% ee). Moreover, using two different DES mixture...

2016
Gastón Silveira-Dorta Sergio J Álvarez-Méndez Víctor S Martín José M Padrón

An improved protocol for the synthesis of enantiomerically pure allylic amines is reported. N-Protected α-amino esters derived from natural amino acids were submitted to a one-pot tandem reduction-olefination process. The sequential reduction with DIBAL-H at -78 °C and subsequent in situ addition of organophosphorus reagents yielded the corresponding allylic amines without the need to isolate t...

Journal: :Angewandte Chemie 2016
Benjamin Schumann Sharavathi G Parameswarappa Marilda P Lisboa Naresh Kottari Fabio Guidetti Claney L Pereira Peter H Seeberger

The glycosylation reaction is the key transformation in oligosaccharide synthesis, but it is still difficult to control in many cases. Stereocontrol during cis-glycosidic linkage formation relies almost exclusively on tuning the glycosylating agent or the reaction conditions. Herein, we use nucleophile-directed stereocontrol to manipulate the stereoselectivity of glycosylation reactions. Placin...

Journal: :Organic & biomolecular chemistry 2011
Sajjad Ahmad Lynne H Thomas Andrew Sutherland

The stereoselective synthesis of a series of di- and tri-hydroxylated aminocyclohexane derivatives has been developed. A one-pot, two step tandem process involving an Overman rearrangement and a ring closing metathesis reaction has been utilised for the asymmetric synthesis of (1S)-1-(2',2',2'-trichloromethylcarbonylamino)cyclohexa-2-ene. Oxidation of this cyclohexene derivative was then studie...

Journal: :Organic & biomolecular chemistry 2011
John S Carey Somhairle MacCormick Steven J Stanway Aphiwat Teerawutgulrag Eric J Thomas

Alk-2-enylstannanes with 4-, 5- and 6-alkoxy- or -hydroxy-substituents are transmetallated stereoselectively with tin(iv) halides to generate allyltin trihalides which react with aldehydes to give (Z)-alk-3-enols with useful levels of 1,5-, 1,6- and 1,7-stereocontrol. Alk-2-enylstannanes with a stereogenic centre bearing a hydroxy or alkoxy group at the 4-, 5- or 6-position, react with overall ...

2010
Jakub Saadi Irene Brüdgam Hans-Ulrich Reissig

A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also infl...

2016
Carolin Bisterfeld Thomas Classen Irene Küberl Birgit Henßen Alexander Metz Holger Gohlke Jörg Pietruszka

The 2-deoxy-d-ribose-5-phosphate aldolase (DERA) offers access to highly desirable building blocks for organic synthesis by catalyzing a stereoselective C-C bond formation between acetaldehyde and certain electrophilic aldehydes. DERA´s potential is particularly highlighted by the ability to catalyze sequential, highly enantioselective aldol reactions. However, its synthetic use is limited by t...

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