Tandem-Michael-Addition von 1-Cyanenaminen an Cyclohexenone. Ein neuer Zugang zu Bicyclo[2.2.2]octanonen
作者:Hubertus Ahlbrecht、Manfred Dietz、Claudia Schön、Volker Baumann
DOI:10.1055/s-1991-26398
日期:——
Tandem-Michael Addition of 1-Cyanoenamines to Cyclohexenones A New Access to Bicyclo[2.2.2]octanones Bicyclo[2.2.2]octane-2,5-diones 5 are easily obtained via tandem Michael addition of 2-(N-methylanilino)acrylonitrile (2) with deprotonated cyclohexenones 1. The reaction is highly anti-stereoselective with respect to substituents on C-4 and C-5 of the cyclohexenone and is blocked by disubstitution on C-4. 6-Acylbicyclo[2.2.2]octan-2-ones 25 are obtained by tandem Michael addition of deprotonated 2-(N-methylanilino) but-2-enonitrile (18) with cyclohexenone and subsequent protonation or alkylation. Both reactions gave lower yields or even failed with cyclopentenone and cycloheptenone.
1-氰基亚胺的串联迈克尔加成反应与环己烯酮的应用:获得双环[2.2.2]辛酮的新方法。双环[2.2.2]辛烷-2,5-二酮可通过2-(N-甲基苯胺基)丙烯腈与去质子化的环己烯酮的串联迈克尔加成反应轻松获得。该反应对于环己烯酮的C-4和C-5上的取代基具有高度的反超选择性,并且在C-4上存在双取代时会受到阻碍。6-酰基双环[2.2.2]辛烷-2-酮是通过去质子化的2-(N-甲基苯胺基)丁-2-烯腈与环己烯酮的串联迈克尔加成反应获得的,随后经历质子化或烷基化反应。这两种反应在环戊烯酮和环庚烯酮中都得到了较低的产率,甚至失败。