Copper-Catalyzed Coupling Reaction of C−OMe Bonds Adjacent to a Nitrogen Atom with Terminal Alkynes
摘要:
The cross coupling of the C-OMe bond adjacent to a nitrogen atom in dialkoxy-N,N-dialkylmethanamines with terminal alkynes was efficiently approached in the presence of copper catalyst under mild conditions to give 3-amino-1,4-diynes in good yields. The reaction is promoted by phosphine ligands and the chemistry provides a simple and efficient route to 3-amino-1,4-diynes. Importantly, the Michael addition occurred with as-prepared 3-amino-1,4-diynes to give the useful Michael-adducts containing tert-alkylamines in a very convenient way. Further studies revealed that (E)-1,5-diarylpent-1-en-4-yn-3-one was formed through the rearrangement by using the neutral alumina column, and the corresponding imine 2-(1,5-diphenylpent-2-en-4-ynylideneamino)ethanol was obtained in the presence of AgOTf.
Aminopyridine Carbamic Acid Esters: Synthesis and Potential as Acetylcholinesterase Inhibitors and Acetylcholine Releasers
作者:Gregory M. Shutske、John D. Tomer、Kevin J. Kapples、Nicholas J. Hrib、John G. Jurcak、Gina M. Bores、Francis P. Huger、Wayne Petko、Craig P. Smith
DOI:10.1002/jps.2600810419
日期:1992.4
intermediate in the synthesis of 2b, demonstrated surprisingly good cholinesterase inhibition (IC50 was 9.4 microM) but showed no activity as a release. A precursor to 7a, N-(3-hydroxy-4-pyridyl)-N',N'-dimethylformamidine (6a), showed some activity in release but was not an esterase inhibitor, whereas the precursor to 6a, 4-amino-3-pyridinol (5a), was a potent releaser. A new synthesis of 5a, based on
Cu-catalyzed three-component reaction of alkyne, azides (sulfonyl or phosphoryl azides), and N,N-dialkyloxyformamide dialkyl acetal via electrophilic addition of immonium ion to copper ketenimine is reported. This new protocol for the preparation of α,β-unsaturated amidine derivatives appears to offer high yield, mild conditions, and wide substrate scope. The reaction might involve the processes of
A total synthesis of (±)-α-cyclopiazonic acid using a cationic cascade as a key step
作者:Charlotte M. Griffiths-Jones (née Haskins)、David W. Knight
DOI:10.1016/j.tet.2011.08.094
日期:2011.11
The indole alkaloid α-cyclopiazonic acid 1 has been synthesised by a route, which features at its core an acid-catalysed cationic cascade cyclisation terminated by a sulfonamide group.
Enamine–azide [2+3]-cycloaddition as a method to introduce functional groups into fluorescent dyes
作者:Nadezhda S. Baleeva、Snizhana O. Zaitseva、Konstantin S. Mineev、Anastasia V. Khavroshechkina、Marina B. Zagudaylova、Mikhail S. Baranov
DOI:10.1016/j.tetlet.2019.01.007
日期:2019.1
functional groups into fluorescentdyes, based on the [2+3]-cycloaddition reaction of “terminal” enamines with azides. The synthesis of such “terminal” enamines is carried out by the condensation of formamide acetals with a methyl group that is influenced by a strong electron withdrawing group. Thus, the proposed functionalization technique requires only the presence of a methyl group in the relevant position
Ortho-nitrotoluenes are condensed with formamide acetals to yield the corresponding otho-nitro-.beta.-aminestyrenes which undergo cyclization upon reduction to yield indoles.