A versatile and convenient route to ketone C-pyranosides and ketone C-furanosides from unprotected sugars
作者:Junfeng Wang、Qin Li、Zemei Ge、Runtao Li
DOI:10.1016/j.tet.2011.11.029
日期:2012.1
Both ketone C-pyranosides (in up to 97% yields) and C-furanosides (in 83–97% yields) could be prepared, respectively, from the condensations of pentane-2,4-dione and various unprotected sugars in sodium carbonate aqueous media by adjusting the reaction conditions.
The present invention relates to novel C-glycoside compounds of given absolute configuration, to a process for synthesising them and to compositions containing them. The invention also relates to the cosmetic use of these C-glycoside compounds as agents to stimulate the synthesis of glycosaminoglycans containing a D-glucosamine and/or N-acetyl-D-glucosamine residue, advantageously hyaluronic acid, and/or of proteoglycans, advantageously proteoglycans containing hyaluronic acid, by fibroblasts and/or keratinocytes. The invention also relates to a cosmetic process for treating keratin materials using a composition containing at least one C-glycoside compound according to the invention.
A novel and efficient direct aldol condensation from ketones and aromatic aldehydes catalyzed by proline–TEA through a new pathway
作者:Jun-feng Wang、Meng Lei、Qin Li、Ze-mei Ge、Xin Wang、Run-tao Li
DOI:10.1016/j.tet.2009.04.052
日期:2009.6
aldol condensation from various ketones and a wide range of aldehydes was catalyzed by l-proline–TEA (triethylamine) in MeOH at room temperature, affording the corresponding (E)-α,β-unsaturated ketones in excellent yields. By using the method, some complicated (E)-α,β-unsaturated ketone C-glycosides were obtained from unmodified ketone C-glycosides and aldehydes. This reaction proceeds through a new
Preparation of saturated and unsaturated fatty acid hydrazides and long chain C-glycoside ketohydrazones
作者:Chrissie A. Carpenter、James A. Kenar、Neil P. J. Price
DOI:10.1039/c0gc00372g
日期:——
products free of starting methyl esters or triacylglycerols. These hydrazide molecules have been used, in conjunction with carbohydrateC-glycoside ketones, to prepare long chain C-glycoside ketohydrazones. This preparation does not require protecting groups or anomeric activation, and various C-glycoside ketohydrazones that retain the closed ring conformation of the parent sugars are described. These
The synthesis of C-glycosides in water or in the absence of any solvent from free sugars and β-keto phosphonates is reported. The methodology permits a one-step access to C-glycoside amphiphiles in moderate-to-good yields. The selectivity (α/β and furanoside/pyranoside) is discussed and a process that leads to pure β-C-pyranosides is also described.