Study on the selectivity in the electrophilic monofluorination of 2,3-allenoates with Selectfluor™: an efficient synthesis of 4-fluoro-2(5H)-furanones and 3-fluoro-4-oxo-2(E)-alkenoates
Reaction of 2,3-Allenoates with TsNBr<sub>2</sub> in the Presence of Base: A Facile Highly Stereoselective Synthesis of (1<i>E</i>,2<i>E</i>)-3-Bromo-4-oxo-<i>N</i>‘-tosyl-2-alkenoxylimidic Acid Ethyl Esters
作者:Ruwei Shen、Xian Huang
DOI:10.1021/jo070239z
日期:2007.5.1
A novel reaction pathway of 2,3-allenoates with an electrophile (TsNBr2) in the presence of K2CO3 to produce (1E,2E)-3-bromo-4-oxo-N‘-tosyl-2-alkenoxylimidic acidethylesters is reported. The reaction proceeds in a highly stereoselective fashion. A plausible mechanism to rationalize this reaction is also proposed.
在K 2 CO 3存在下2,3-脲基酸酯与亲电试剂(TsNBr 2)的新反应途径产生(1 E,2 E)-3-bromo-4- oxo- N'-甲苯磺酰基-2-报道了烯氧基氧酰亚胺酸乙酯。反应以高度立体选择性的方式进行。还提出了合理化该反应的合理机制。
Studies on electrophilic addition reaction of 2,3-allenoates with PhSeCl
作者:Guofei Chen、Chunling Fu、Shengming Ma
DOI:10.1016/j.tet.2006.02.053
日期:2006.5
butenolides were prepared from 2,3-allenoates and PhSeCl in the presence of water. The yields of the products depend largely on the structures of 2,3-allenoates. The addition of water is crucial for some of this electrophilic cyclization. The reaction of simple unsubstituted methyl 2,3-butadienoate afforded methyl 4-chloro-3-phenylselanylbut-2(Z)-enoate in good yield and stereoselectivity.
Electrophilic Interaction of 2,3-Allenoates with PhSeCl. An Unexpected Highly Stereoselective Synthesis of 3-Phenylseleno-4-oxo-2(<i>E</i>)-alkenoates
作者:Guofei Chen、Chunling Fu、Shengming Ma
DOI:10.1021/jo061680c
日期:2006.12.1
We have previously reported an efficient synthesis of beta-phenylselenium-substituted butenolides via electrophilic cyclization of 2,3-allenoates with PhSeCl in aqueous MeCN. However, when 2,3-allenoates were treated with PhSeCl in MeCN, 3-phenylseleno-4-oxo-2(E)-alkenoates were formed unexpectedly. The addition of Li2CO3 improved the yield and the selectivity of the reaction. A possible mechanism involving a decomposition of selenate esters was proposed.