Thermodynamic epimeric equilibration and crystallisation-induced dynamic resolution of lobelanine, norlobelanine and related analogues
作者:Z. Amara、G. Bernadat、P.-E. Venot、P. Retailleau、C. Troufflard、E. Drège、F. Le Bideau、D. Joseph
DOI:10.1039/c4ob01787k
日期:——
β-aminoketone subunit, lobelanine is prone to self-catalyze mutarotation in solution. Through the synthesis of original lobelanine analogues, we studied the influence of (i) the size of the central heterocycle, (ii) the bulkiness of the nitrogen protecting group, and (iii) the phenacyl arm substituent on the thermodynamic equilibrium and its displacement by crystallisation-induced dynamic resolution
The dual reactivity of Weinreb amides applied to the late-stage divergent functionalisation of <i>meso</i> pyrrolidines
作者:Hamza Boufroura、Laurent Sevaille、Nicolas Gigant、Emmanuelle Drège、Delphine Joseph
DOI:10.1039/c8nj01975d
日期:——
By exploiting the dual reactivity of a Weinrebamide moiety, i.e. nucleophilic addition or N–O reductive cleavage, a series of diversified symmetrical and dissymmetrical pyrrolidine analogues of lobelanine were synthesized from simple and readily available buildingblocks. Diversity is introduced at a late stage by using a wide variety of readily available organolithium and organomagnesium reagents
Solvent-free double aza-Michael under ultrasound irradiation: diastereoselective sequential one-pot synthesis of pyrrolidine Lobelia alkaloids analogues
作者:Zacharias Amara、Emmanuelle Drège、Claire Troufflard、Pascal Retailleau、Delphine Joseph
DOI:10.1039/c2ob25963j
日期:——
Novel 2,5-meso-pyrrolidines have been straightforwardly synthesized from readily available symmetrical double Michael acceptors. The key step rested on an aza-Michael addition of primary alkylamines to bis-enones. Competitive Rauhut–Currier and aza-Michael reactions have been highlighted in protic solvent. Ultrasound activation associated with solvent-free conditions led to the expected pyrrolidines in quantitative yields and excellent stereoselectivities. The optimized conditions have been extended to the sonochemical synthesis of pyrrolidine Lobelia alkaloids analogues in short sequences.