نتایج جستجو برای: stereoisomeric group

تعداد نتایج: 979523  

Journal: :Chirality 1992

Stereoisomers are molecules that are identical in atomic constitution and bonding, but differ in the three-dimensional arrangement of the atoms. For the purpose of this document, the stereoisomeric pairs of greatest interest are those with one or more asymmetric (chiral) centers whose enantiomers (individual stereoisomers) are mirror images. They have essentially identical physical (except for ...

2014
Rakesh H. Vekariya Ruzhang Liu Jeffrey Aubé

An intramolecular Huisgen cycloaddition of an interconverting set of isomeric allylic azides with alkynes affords substituted triazoles in high yield. The stereoisomeric vinyl-substituted triazoloxazines formed depend on the rate of cycloaddition of the different allylic azide precursors when the reaction is carried out under thermal conditions. In contrast, dimerized macrocyclic products were ...

Journal: :Journal of Synthetic Organic Chemistry, Japan 1985

Journal: :Chemical and Pharmaceutical Bulletin 1958

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده علوم انسانی 1392

this study investigated how group formation method, namely student-selected vs. teacher-assigned, influences the results of the community model of teaching creative writing; i.e., group dynamics and group outcome (the quality of performance). the study adopted an experimental comparison group and microgenetic research design to observe the change process over a relatively short period of time. ...

2009
Katarzyna Urbaniak Małgorzata Domagała Manfred Zabel

The thermal reaction of trans-1-methyl-2,3-diphenylaziridine (trans-1a) with aromatic and cycloaliphatic thioketones 2 in boiling toluene yielded the corresponding cis-2,4-diphenyl-1,3-thiazolidines cis4 via conrotatory ring opening of trans-1a and a concerted [2þ 3]-cycloaddition of the intermediate (E,E)-configured azomethine ylide 3a (Scheme 1). The analogous reaction of cis-1a with dimethyl...

Journal: :Molecules 2018
Yuanzhi He Feixue Chen Meijing Sun Huifang Gao Zewang Guo Hui Lin Jiebo Chen Wensong Jin Yunlong Yang Liaoyuan Zhang Jun Yuan

(3S)-Acetoin and (2S,3S)-2,3-butanediol are important platform chemicals widely applied in the asymmetric synthesis of valuable chiral chemicals. However, their production by fermentative methods is difficult to perform. This study aimed to develop a whole-cell biocatalysis strategy for the production of (3S)-acetoin and (2S,3S)-2,3-butanediol from meso-2,3-butanediol. First, E. coli co-express...

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