Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: A New Strategy for the Synthesis of Spiro and Bridged Heterocycles
摘要:
Novel bicyclic and tetracyclic spirocycles and tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of latent bis-nucleophiles to alpha,beta-unsaturated N-acyliminium ions.
Guided by nature: A flexible and epimerization‐free approach for the asymmetricsyntheses of melleumin A and fouranalogues of melleumins A and B was developed, which allowed confirming the stereochemistry at C‐4 of melleumin A, and revealed that the unnatural 4‐epi‐melleuminB possesses a modest inhibitoryactivity on Wntsignaling.
Synthesis of spirocyclic heterocycles from α,β-unsaturated <i>N</i>-acyliminium ions
作者:Thanphat Thaima、Arife Yazici、Chiramet Auranwiwat、Anthony C. Willis、Uta Wille、Thunwadee Limtharakul、Stephen. G. Pyne
DOI:10.1039/d0ob02075c
日期:——
The reactions of α,β-unsaturated N-acyliminium ions, generated in situ from 4(S)-O-substitutedhydroxy-5-hydroxy-5-vinyl-N-alkylpyrrolidin-2-ones, with allylsilanes and indoles leading to the formation of spirocyclic heterocycles, are reported. Six single crystal X-ray structures and extensive 2D NMR experiments confirmed the structures and stereochemistries of these products. In addition, computational
Enantioselective Synthesis of the <i>R</i>-Enantiomer of the Feeding Deterrent (<i>S</i>)-Ypaoamide
作者:Jie Chen、Pei-Qiang Huang、Yves Queneau
DOI:10.1021/jo901557h
日期:2009.10.2
The enantioselective synthesis of the R-enantiomer of the marine natural product (S)-ypaoamide (5) is reported. The synthesis features both a flexible racemization-free approach to the 5-substituted 3-pyrrolin-2-one segment, and a lipase (CCL)-promoted deacetylation reaction to reach the orthogonal deprotection. Through this work the absolute configuration of the natural ypaoamide was determined as S.