Stereoselective Synthesis of Tertiary Ethers through Geometric Control of Highly Substituted Oxocarbenium Ions
作者:Lei Liu、Paul E. Floreancig
DOI:10.1002/anie.201002281
日期:2010.8.9
Fully substituted, fully controlled! The geometries of 1,1‐disubstituted oxocarbeniumions and the conformations of oxocarbeniumions that contain a tertiary stereocenter can be predicted based on simple models. These models have been applied to highlystereoselective syntheses of tetrahydropyran derivatives that contain tertiaryethers (see scheme; RL, RS, and RN represent large, small, and nucleophilic
全面换人,全面控制!1,1-二取代的氧碳鎓离子的几何形状和包含叔立构中心的氧碳鎓离子的构象可以基于简单的模型来预测。这些模型已应用于含有叔醚的四氢吡喃衍生物的高度立体选择性合成(参见方案;R L、RS和 R N分别代表大基团、小基团和亲核基团)。
Transferts d'hydrogènes dans les cations radicaux ethylène-acetals dérivés de cyclopentanones et cyclohexanones
作者:H. E. Audier、J. C. Tabet、M. Fetizon
DOI:10.1002/hlca.19850680412
日期:1985.6.26
Hydrogen Transfer during Decompositions of Molecular Ions of Acetals Derived from Substituted Cyclopentanones and Cyclohexanones
缩合环戊酮和环己酮衍生的缩醛缩合分子离子过程中的氢转移
A remarkable iodine-catalyzed protection of carbonyl compounds
作者:Bimal K. Banik、Marin Chapa、Jocabed Marquez、Magda Cardona
DOI:10.1016/j.tetlet.2005.01.176
日期:2005.3
report here a remarkably simple molecular iodine-catalyzed protection method for various carbonyl compounds as ketals in a general reaction. The iodine-catalyzed reaction of mandelic acid and lacticacid with several aldehydes has furnished a highly diastereoselectivesynthesis of cis and trans dioxolanones.
A New Ready, High-Yielding, General Procedure for Acetalization of Carbonyl Compounds
作者:Romualdo Caputo、Carla Ferreri、Giovanni Palumbo
DOI:10.1055/s-1987-27955
日期:——
Carbonyl compounds are smoothly and rapidly acetalized by treatment with alcohols, in anhydrous acetonitrile, in the presence of polystyryl diphenyl phosphine - iodine complex as catalyst. Open and cyclic acetals, including 1,3-dioxolanes, 1,3-oxathiolanes, and 1,3-dithiolanes, of miscellaneous aldehydes and ketones have been successfully prepared in this way. The isolation of the product is very easily performed, by simple filtration of the polymer-linked phosphine oxide which is formed in the reaction.
Carbonyl compounds 1 were converted to the corresponding 1,3-dioxolanes 2 and 1,3-dioxanes 4 with ethylene glycol and 2,2-dimethyl-1,3-propandiol, respectively, in the presence of 1-3 mol% of N-(benzyl, 4-methylbenzyl or 4-methoxybenzyl)-2(or -4)-cyanopyridinium hexafluoroantimonates 3. The catalyst 3d was also effective for the tetrahydropyranylation.