Reductive Alkylation of γ-Cyano-α,β-unsaturated Ketones. A Modified Robinson Annulation Process to α,α-Disubstituted β,γ-unsaturated Cyclohexanone System
作者:Chia-Liang Tai、Tai Wei Ly、Jen-Dar Wu、Kak-Shan Shia、Hsiang-Jang Liu
DOI:10.1055/s-2001-10788
日期:——
Reductive alkylation of various 4-cyano-2-cyclohexenones, readily available from α-cyano ketones via a Robinson annulation process, gave rise to the corresponding 2,2-disubstituted-3-cyclohexenone derivatives in a completely regioselective manner. Application of this methodology resulted in an efficient synthesis of the marine natural product nanaimoal in racemic form.
Stereochemistry of theRobinson Anellation: Studies on the Mode of Formation of the Intermediate Hydroxy Ketones
作者:Cornelius Nussbaumer
DOI:10.1002/hlca.19900730607
日期:1990.9.19
stereochemical outcome of the base-catalyzed cyclization of diketones 5–8 has been investigated under protic conditions (Scheme 3). The more stable trans-fused ketols are preferentially formed in kinetically controlled aldol reactions, when the incipient angular substituent R = H (6 10a) or CN (7 11a, 8a 12a). For R = Me (as in 5), axial attack of the side-chain enolate doublebond on the ring CO group results
reactions, giving the corresponding 2,2-disubstituted-3-cyclohexenone derivatives in a completely regioselective manner. This newly developed methodology has been successfully applied towards the totalsynthesis, in racemic form, of the marine natural product nanaimoal.