New synthetic approach to α-fluoro-β-arylvinyl sulfones and their application in Diels–Alder reactions
作者:Aleksey V. Shastin、Valentine G. Nenajdenko、Vasiliy M. Muzalevskiy、Elizabeth S. Balenkova、Roland Fröhlich、Günter Haufe
DOI:10.1016/j.tet.2008.07.097
日期:2008.10
obtained as the major products. From these cycloadducts, as a proof of principle, p-toluenesulfinic acid was eliminated to give 2-fluoro-3-(4-nitrophenyl)norbornadiene, the formal [4+2]-cycloadduct of cyclopentadiene and 1-fluoro-2-(4-nitrophenyl)acetylene, or the corresponding diphenylisobenzofuran cycloadducts, respectively. This reaction was not successful when other β-hydrogen atoms are accessible for
阐述了通往α-氟-β-芳基乙烯基砜的新途径。β-溴-β-氟苯乙烯与4-甲基苯基亚磺酸钠的反应以最大的94:6立体选择性和72-90%的产率进行。发现形成的α-氟-β-芳基乙烯基砜是与简单的1,3-二烯进行Diels-Alder反应的良好的亲二烯体。从相应的(É)构型亲二烯体和环戊二烯,cycloadducts轴承氟取代基在外型-位被主要形成,同时与diphenylisobenzofuran的产品内的氟的-orientation作为主要产物而获得。从这些环加合物中,作为原理证明,p除去-甲苯亚磺酸,得到2-氟-3-(4-硝基苯基)降冰片二烯,环戊二烯和1-氟-2-(4-硝基苯基)乙炔的正式[4 + 2]-环加合物或相应的二苯基异苯并呋喃环加合物, 分别。当其他β-氢原子可被消除时,该反应并不成功。