1,721,048 research outputs found
[Virological and clinical aspects of multiple hepatitis virus infections: preliminary data of an italian multicentre study]
No full textAspetti virologici e clinici delle infezioni multiple da virus epatitici: dati preliminari di uno studio multicentrico nazionale.
No full textDesign, Synthesis, Conformational Analysis and Application of Azabicyclo-alkane Amino Acids as Constrained Dipeptide Mimics
No full textIn the field of peptidomimetics, major efforts have been focused on the design and synthesis of conformationally constrained compounds that mimic or induce reverse-turn motifs of peptides and proteins which are thought to play important roles in recognition and biological activity. In this regard, a particularly attractive class of compounds are the azabicyclo[X.Y.O]alkane dipeptide mimics. We present our efforts on the design, synthesis, and conformational analysis of a series of rigid surrogates of dipeptide units for applications within constrained peptide analogues, for employment as inputs for combinatorial science and biological applications. Several general and versatile synthetic approaches have been conceived to deliver a variety of enantiornerically pure azabi-cycloalkanes. All of these methodologies rely on the construction of a 5-, 6-, or 7-membered lactam, on a preformed proline based nucleus. Different strategies were adopted to perform the key cyclization step: a) radical addition to an olefinic double bond, b) alkylation of a malonate enolate, c) ring-closing metathesis (RCM), and d) lactam bond formation
Application of structure-based thermodynamic calculations to the rationalization of the enantioselectivity of subtilisin in organic solvents
No full textThe effect of organic solvents on the selectivity of lyophilized or CLEC
(cross-linked enzyme crystals)-subtilisin in the resolution of
sec-phenethyl alcohol and trans-sobrerol was studied. A theoretical
model, that tries to predict solvent effects on enantioselectivity only
as a function of the activity coefficients of the desolvated part of the
substrate in the relevant transition state of the reaction (Ke, T.;
Wescott, C. R.; Klibanov, A. M. J. Am. Chem. Sec., 1996, 118, 3366) was
examined and shown to agree poorly with the experimental data. The
tetrahedral intermediate was studied with MonteCarlo molecular
mechanics, and the activity coefficients were calculated with UNIFAC.
(C) 1998 Elsevier Science Ltd. All rights reserved
Dibenzylaminoacetates as Useful Synthetic Equivalents of Glycine in the Synthesis of alpha-Amino-beta-hydroxyacids
No full textAsymmetric Synthesis by the use of Norephedrine-Derived 2-Methoxy-Oxazolidines. Part Four: the Synthesis of Enantiomerically Enriched Polyhydroxylated Building Blocks
No full text
Stereoselective aldol condensations via alkenyloxy dialkoxy boranes: mechanistic and stereochemical details
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