نتایج جستجو برای: diastereoisomers
تعداد نتایج: 351 فیلتر نتایج به سال:
Chirality reversal between enantiomers is of great importance in both fundamental science and practical applications chiroptics, biomedicine, analytical chemistry. Here, we demonstrate an abrupt sign circular dichroism (CD) artificial plasmonic diastereoisomers, which are a kind stereo twisted metamolecules with different strength deformations. The the CD response reversed same wavelength regio...
Phosphine-catalyzed [4+1] annulation of 2-tosylaminochalcones with allenoates has been achieved, giving trans-2,3-disubstitued indolines as major diastereoisomers in moderate to good yields.
[Figure: see text]. A series of donor-acceptor pretzelanes has been synthesized, using self-assembly and template-directed protocols, and the dynamic processes that these pretzelanes undergo have been investigated in solution. These compounds exist as libraries of diastereoisomers as a result of their multiple stereoelements, which are dynamically interconverted by several different, in some ca...
N-Heterocyclic carbene-catalyzed reaction of 2-aroylvinylcinnamaldehydes with 2-aroylvinylchalcones proceeded via a triple Michael addition and intramolecular lactonization cascade to produce novel 9-(2-aroyl-3-aroylmethyl-1-indanyl)-3-arylindeno[2,1-c]pyran-1-ones in good yields with high diastereoselectivity. This reaction constructed six contiguous stereogenic centers in a single reactive ev...
The levels of degradation of cefetamet pivoxil (CAT), cefuroxime axetil (CAE), and cefpodoxime proxetil (CPD) in 0.6 M phosphate buffer (pH 7.4) and human intestinal juice (pH 7.4) at 37 degreesC over 24 h were compared. Significant differences in the time courses of degradation and in the patterns of degradation products were observed. (i) The relative proportions of the Delta2- and Delta3-cep...
BACKGROUND It is well established that vicinal fluorines (RCHF-CHFR) prefer to adopt a gauche rather than an anti conformation when placed along aliphatic chains. This has been particularly recognised for 1,2-difluoroethane and extends to 2,3-difluorobutane and longer alkyl chains. It follows in these latter cases that if erythro and threo vicinal difluorinated stereoisomers are compared, they ...
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