<i>exo</i>-Stereoselectivity in<i>Diels-Alder</i>Addition of Halogenocyclopropenes to Butadienes and Furans
作者:Paul Müller、Gérald Bernardinelli、Jean Pfyffer、Domingo Rodriguez、Jean-Pierre Schaller
DOI:10.1002/hlca.19880710306
日期:1988.5.4
The stereochemistry of the Diels-Alder reaction of 1,2-dichloro-3,3-difluorocyclopropene (5a) to 1,4-diphenyl-1,3-butadiene (6) and 1,3-diphenylisobenzofuran (7) was unambiguously established by X-ray structure determination. In all cases known so far, tetrahalogenocyclopropenes add exo to open-chain dienes and furans. The previously reported exo-addition product (2a) of l-bromo-2-chlorocyclopropene
明确确立了1,2-二氯3,3-二氟环丙烯(5a)与1,4-二苯基-1,3-丁二烯(6)和1,3-二苯基异苯并呋喃(7)的Diels - Alder反应的立体化学。通过X射线结构测定。到目前为止,在所有已知情况下,四卤代环丙烯都将exo添加到开链二烯和呋喃中。先前报道的外型-addition产物(2A 1-溴-2- chlorocyclopropene(的)5B)至7允许的其它添加的立体化学的分配图5b到呋喃。exo-添加通常占主导地位,但在某些情况下,还会形成内加合物。这与文献中的报道相反,即5b在开链二烯中优先添加内含物。