Domino 6π-Electrocyclization/Diels-Alder Reactions on 1,6-Disubstituted (E,Z,E)-1,3,5-Hexatrienes: Versatile Access to Highly Substituted Tri- and Tetracyclic Systems
作者:Regina von Essen、Daniel Frank、Hans Wolf Sünnemann、Denis Vidović、Jörg Magull、Armin de Meijere
DOI:10.1002/chem.200500560
日期:2005.11.4
Diels-Alder reaction, when performed as a one-pot domino process, provided direct access to Diels-Alder products of intermediately formed 6pi-electrocyclization products, for example from the 1,3,5-hexatrienes 1a,b, 2a,b, 3b and TCNE to the corresponding tricyclic products 17a,b, 14a,b, 18b in moderate to good yields (27-80%) depending on the nature of the alkoxycarbonyl group. Such sequential reactions with
(E,Z,E)-1,3,5-己三烯1a,2a,b和3b在加热到200-215摄氏度后的15-30分钟内经历6pi电环化。为了稳定,类似的环戊烯-和环庚烯-退火的衍生物7a和9b在后处理过程中很容易脱氢成相应的芳族化合物10a和12b。环己二烯衍生物8a,b用于与4-苯基-3H-1,2,4-三唑啉-3,5-二酮(PTAD)和四氰基乙烯(TCNE)的热Diels-Alder反应中,得到预期的[4 + 2 ]环加合物13a和14a的收率很高(60%和78%)。最初形成的8a环加合物和乙酰二羧酸二甲酯(DMAD)进行随后的Diels-Alder逆反应,得到四氢萘11b(47%)。在高压(10 kbar)下,环加合物15a是在室温下形成的,可以44%的收率分离出来。TCNE和在高压下具有8a的N-苯基马来酰亚胺也导致了[4 + 2]环加合物14a和16a的高收率(60%和77%)。6pi电环化反应和