Direct <i>anti</i>
Glycolate Aldol Reaction of Protected Chiral <i>N</i>
-Hydroxyacetyl Thiazolidinethiones with Acetals Catalyzed by a Nickel(II) Complex
作者:Juan Manuel Romo、Pedro Romea、Fèlix Urpí
DOI:10.1002/ejoc.201901097
日期:2019.9.30
Tiny amounts of commercially available and easy to handle (Me3P)2NiCl2 trigger the stereoselective aldol addition of chiral N‐2‐pivaloyloxyacetyl thiazolidinethione 7 to acetals to provide the corresponding anti glycolate adducts in a highly efficient manner.
The present invention relates to a process for making indenol esters or ether from an α-substituted cinnamic aldehyde derivative such as an acetal or an acylal. This reaction is promoted by the use of strong mineral acids, sulphonic acids, acidic zeolites or Lewis acids.
The use of 1,2-O-isopropylidene-α-d-xylofuranose as a chiral auxiliary in asymmetric cyclopropanation reactions
作者:José M. Vega-Pérez、Ignacio Periñán、Fernando Iglesias-Guerra
DOI:10.1016/j.tetasy.2009.02.062
日期:2009.5
1,2-O-isopropylidene-d-xylofuranose, as a chiralauxiliary, is described. The Simmons–Smith cyclopropanationreaction of the corresponding alkenylidene derivatives with CH2I2/ZnEt2, in different reaction conditions, took place with high stereoselectivity. The diastereomeric excess in each case depended on the solvent and the temperature used in the reaction. The absolute configuration of the new stereogenic
描述了衍生自作为手性助剂的1,2 - O-异亚丙基-d-木呋喃糖的环丙基亚甲基缩醛的立体选择性合成。在不同的反应条件下,相应的链烯基衍生物与CH 2 I 2 / ZnEt 2的Simmons-Smith环丙烷化反应具有很高的立体选择性。在每种情况下,非对映异构体过量取决于反应中所用的溶剂和温度。通过手性助剂的环丙烷部分的酸水解确定了形成的新的立体异构中心的绝对构型,该手性助剂也被回收了。
Stereoselective cyclopropanation of unsaturated acetals, using carbohydrates with d-gluco, l-rhamno and d-xylo configurations as chiral auxiliaries
作者:José M. Vega-Pérez、Ignacio Periñán、Margarita Vega、Fernando Iglesias-Guerra
DOI:10.1016/j.tetasy.2008.06.018
日期:2008.7
with CH2I2/ZnEt2 took place with different stereoselectivity, depending on the configuration on the acetal carbon, the size of the acetal ring, the sugar configuration, the protecting group of the hydroxyl groups of the sugar and the substitution of the unsaturated system. The stereochemistry of the new stereogenic centres was then determined by acid hydrolysis of the cyclopropane moiety of the chiral
Stereoselective epoxidation of alkenylidene acetals derived from carbohydrates with d-allo, d-altro, d-galacto, d-gluco and d-xylo configurations
作者:José M. Vega-Pérez、Margarita Vega、Eugenia Blanco、Fernando Iglesias-Guerra
DOI:10.1016/j.tetasy.2007.07.015
日期:2007.8
The synthesis of 2,3-epoxypropylidene acetals of sugar derivativesfrom N-acetyl-2-amino-2-deoxy-d-allopyranose, d-altropyranose, d-galactopyranose, N-acetyl-d-glucosamine, d-glucofuranose and d-xylofuranose is described. The epoxidation with m-CPBA of the corresponding alkenylidene derivatives took place with different stereoselectivities depending upon the sugar configuration, the protecting group