643754-23-8Relevant academic research and scientific papers
Generation of All-Carbon Quaternary Stereocenters at the C-3 Carbon of Lactams via [3,3]-Sigmatropic Rearrangement and Revision of Absolute Configuration: Total Synthesis of (-)-Physostigmine
Pandey, Ganesh,Khamrai, Jagadish,Mishra, Akash
supporting information, p. 166 - 169 (2018/01/17)
A diastereoselective (up to >99%) route to all carbon quaternary stereocenters at the C-3 position of cyclic lactams has been developed via Johnson-Claisen rearrangement of ?-hydroxy-α,β-unsaturated lactams. It has been observed that olefin geometry plays an important role in the development of the absolute stereochemistry of the product. Dependence of product configuration on the olefin geometry is explained by postulating probable transition states. The success of this method has been shown for multigram-scale synthesis of these substituted lactams from commercially available cheap starting materials. The synthetic usefulness of this method is also demonstrated by carrying out the total synthesis of (a-)-physostigmine.
Natural α-methylenelactam analogues: Design, synthesis and evaluation of α-alkenyl-γ and δ-lactams as potential antifungal agents against Colletotrichum orbiculare
Delong, Wang,Lanying, Wang,Yongling, Wu,Shuang, Song,Juntao, Feng,Xing, Zhang
, p. 286 - 307 (2017/03/09)
In our continued efforts to improve the potential utility of the α-methylene-γ-lactone scaffold, 62 new and 59 known natural α-methylenelactam analogues including α-methylene-γ-lactams, α-arylidene-γ and δ-lactams, and 3-arylideneindolin-2-ones were synthesized as the bioisosteric analogues of the α-methylenelactone scaffold. The results of antifungal and cytotoxic activity indicated that among these derivatives compound (E)-1-(2, 6-dichlorobenzyl)-3-(2-fluorobenzylidene) pyrrolidin-2-one (Py51) possessed good selectivity with the highest antifungal activity against Colletotrichum orbiculare with IC50?=?10.4?μM but less cytotoxic activity with IC50?=?141.2?μM (against HepG2 cell line) and 161.2?μM (against human hepatic L02?cell line). Ultrastructural change studies performed by transmission electron microscope showed that Py51 could cause important cell morphological changes in C.?orbiculare, such as plasma membrane detached from cell wall, cell wall thickening, mitochondria disruption, a dramatic increase in vacuolation, and eventually a complete loss in the integrity of organelles. Significantly, mitochondria appeared one of the primary targets, as confirmed by their remarkably aberrant morphological changes. Analysis of structure–activity relationships revealed that incorporation of the aryl group into the α-exo-methylene and the N-benzyl substitution increased the activity. Meanwhile, the α-arylidene-γ-lactams have superiority in selectivity over the 3-arylideneindolin-2-ones. Based on the results, the N-benzyl substituted α-(2-fluorophenyl)-γ-lactam was identified as the most promising natural-based scaffold for further discovering and developing improved crop-protection agents.
RETRACTED ARTICLE: An expeditious route to both enantiomers of all carbon quaternary stereocenters at C-3 carbon of lactams via [3,3]-sigmatropic rearrangement: Total synthesis of (-)-physostigmine
Pandey, Ganesh,Khamrai, Jagadish,Mishra, Akash
supporting information, p. 952 - 955 (2015/04/27)
A diastereoselective route to all carbon quaternary stereocenters at the C-3 position of cyclic lactams has been developed via Johnson-Claisen rearrangement of γ-hydroxy-α, β-unsaturated lactams. It has been observed that olefin geometry plays an important role in the development of the absolute stereochemistry of the product. The dependence of the product configuration on the olefin geometry is explained by postulating probable transition states. The success of this method has been shown for the multigram scale synthesis of these substituted lactams from commercially available cheap starting materials. The synthetic usefulness of this method is also demonstrated by carrying out the total synthesis of (-)-physostigmine.
Switching between Novel Samarium(II)-Mediated Cyclizations by a Simple Change in Alcohol Cosolvent
Hutton, Thomas K.,Muir, Kenneth W.,Procter, David J.
, p. 4811 - 4814 (2007/10/03)
(Equation Presented) γ,δ-Unsaturated ketones undergo two very different stereoselective cyclization reactions mediated by samarium(II) iodide depending upon the alcohol cosolvent used in the reaction. Switching between an unprecedented aldol spirocyclizat
