ABSTRACT
A detailed study of amidine synthesis from N-allyl-N-sulfonyl ynamides is described here. Mechanistically, this is a fascinating reaction consisting of diverging pathways that could lead to deallylation or allyl transfer depending upon the oxidation state of palladium catalysts, the nucleophilicity of amines, and the nature of the ligands. It essentially constitutes a Pd(0)-catalyzed aza-Claisen rearrangement of N-allyl ynamides, which can also be accomplished thermally. An observation of N-to-C 1,3-sulfonyl shift was made when examining these aza-Claisen rearrangements thermally. This represents a useful approach to nitrile synthesis. While attempts to render this 1,3-sulfonyl shift stereoselective failed, we uncovered another set of tandem sigmatropic rearrangements, leading to vinyl imidate formation. Collectively, this work showcases the rich array of chemistry one can discover using these ynamides.
Subject(s)
Allyl Compounds/chemistry , Amidines/chemical synthesis , Amines/chemistry , Nitriles/chemical synthesis , Sulfur Compounds/chemistry , Vinyl Compounds/chemistry , Ligands , Molecular StructureABSTRACT
A de novo transformation of N-allyl-N-sulfonyl ynamides to amidines is described featuring a palladium-catalyzed N-to-C allyl transfer via ynamido-palladium-pi-allyl complexes.
Subject(s)
Amidines/chemical synthesis , Lactones/chemical synthesis , Palladium/chemistry , Amidines/chemistry , Catalysis , Imidazoles/chemistry , Lactones/chemistry , Molecular StructureABSTRACT
<p><b>OBJECTIVE</b>To in vestigate the constituents in root of Gentiana macrophylla.</p><p><b>METHOD</b>Various column chromatographic techniques were used for isolation and purification of the principles. The structures were elucidated on the basis of spectral data (UV, IR, MS, 1H-, 13C-NMR etc.) and identified by comparing with standard substance.</p><p><b>RESULT</b>Eight compounds were identified. Four compounds isolated from the chloroform fraction are: 5-carboxyl-3,4-dihydrogen-1H-2-benzopyran-1-one (1), erythrocentauric acid (2), roburic acid (3), oleanolic acid (4). Water fraction gave four known secoiridoid glucosides. They were: gentiopicroside (5), swertiamarine (6), sweroside (7), 6'-O-beta-D-glucosylgentiopicroside (8).</p><p><b>CONCLUSION</b>1 is a novel compound. It was named as erythrocentauric acid. 2 was isolated from genus Gentiana and 8 was isolated from G. macrophylla for the first time.</p>
