Condensation reactions of unprotected tetroses and pentoses with hydroxylamines afforded nitrones, which were easily converted to densely functionalized isoxazolidines in the presence of electron-poor alkenes. The 1,3-dipolarcycloaddition occurred with good facial discrimination of the chiral nitrone but under rather low endo/exo control. Stereochemistry of isomers was ascertained by chemical correlation
Enhancement of Cyclopamine via Conjugation with Nonmetabolic Sugars
作者:Randal D. Goff、Jon S. Thorson
DOI:10.1021/ol300703z
日期:2012.5.18
The Veratrumalkaloid cyclopamine, an inhibitor of cancer stem cell growth, was used as a representative scaffold to evaluate the inhibitory impact of glycosylation with a group of nonmetabolic saccharides, such as d-threose. In a five-step divergent process, a 32-member glycoside library was created and assayed to determine that glycosides of such sugars notably improved the GI50 value of cyclopamine
的藜芦生物碱的环巴胺,癌症干细胞生长的抑制剂,用作代表支架以评价糖基化的一组非代谢的糖类,如抑制冲击d -threose。在一个五步发散过程中,创建并分析了一个 32 成员的糖苷库,以确定这些糖的糖苷显着提高了环巴胺的 GI 50值,而代谢糖,例如d-葡萄糖则没有。
[EN] ISOMERISATION OF C4-C6 ALDOSES WITH ZEOLITES<br/>[FR] ISOMÉRISATION D'ALDOSES EN C4-C6 AVEC DES ZÉOLITES
申请人:UNIV DANMARKS TEKNISKE
公开号:WO2014033311A1
公开(公告)日:2014-03-06
The present invention relates to isomerization of C4-C6 aldoses to their corresponding C4-C6 ketoses. In particular, the invention concerns isomerization of C4-C6 aldoses over solid zeolite catalysts free of any metals other than aluminum, in the presence of suitable solvent(s) at suitable elevated temperatures. C6 and C5 aldose sugars such as glucose and xylose, which are available in large amounts from biomass precursors, are isomerized to fructose and xylulose respectively, in a one or two-step process over inexpensive commercially available zeolite catalysts, containing aluminum as the only metal in the catalyst. The ketoses obtained are used as sweeteners in the food and/or brewery industry, or treated to obtain downstream platform chemicals such as lactic acid, HMF, levulinic acid, furfural, MMHB, and the like. FIG. 7
of the aldolase variant provides control of the sugar size. The stereochemical outcome of the addition was also altered to allow the synthesis of L-glucose and related derivatives. Such engineered biocatalysts may offer new routes for the straightforward synthesis of natural molecules and their analogues that circumvent the intricate enzymatic pathways forged by evolution.
Broadening Deoxysugar Glycodiversity: Natural and Engineered Transaldolases Unlock a Complementary Substrate Space
作者:Madhura Rale、Sarah Schneider、Georg A. Sprenger、Anne K. Samland、Wolf-Dieter Fessner
DOI:10.1002/chem.201002942
日期:2011.2.25
inaccessible by available enzymes, from a [3×8] substrate matrix. Although aliphatic and hydroxylated aliphatic aldehydes were good substrates, D‐lactaldehyde was found to be an inhibitor possibly as a consequence of inactive substratebinding to the catalytic Lys residue. A 1‐hydroxy‐2‐alkanone moiety was identified as a common requirement for the donor substrate, whereas propanone and butanone were inactive