An efficient synthesis of β-methylsulfonylated N-heterocycles via FeCl 3 -catalyzed C(sp 3 )−H dehydrogenation and C(sp 2 )−H methylsulfonylation of inactivated cyclic amines with the promotion and participation of inorganic sodium metabisulfite and dicumyl peroxide (DCP) has been developed. Notably, bifunctional DCP acted not only as an oxidant to promote the dehydrogenation but also as a methyl radical to participate in the sulfone formation. With this protocol, a number of βmethylsulfonylated tetrahydropyridines, tetrahydroazepines, and pyrroles were obtained in a facile one-pot manner.
An efficient synthesis of 1,2,3,4-tetrahydrobenzo[g]quinoline derivatives through PdCl2-catalyzed,
TBHP-promoted,
and toluene-mediated dehydrogenation/[4+2] cycloaddition of saturated
cyclic amines with 2-alkynylbenzaldehydes was developed. On the contrary,
when the reaction medium was changed from toluene to DMSO/H2O, another class of important compounds, naphthyl chain amines, formed
via a dehydrogenation–intermolecular condensation–C–N
bond cleavage–intramolecular condensation pathway, was obtained
with good selectivity.
An efficient and regioselective synthesis of 2ene-1,4-diones, 4-hydroxycyclopent-2-en-1-ones, or 2-(furan-3yl)acetamides is successfully realized through palladiumcatalyzed one-pot multicomponent reactions of allenols with aryl iodides and carbon monoxide in the presence of tertiary amines. Interestingly, the selectivity depends on the substitution patterns of the allenol substrates. To be specific, from the reaction of allenols with no substituent attached on the internal position of the allenic moiety, 2-ene-1,4-diones or 4hydroxycyclopent-2-en-1-ones were formed selectively through carbonylation of aryl iodide followed by acylation of allenol with the in situ formed acyl palladium species, β-hydride elimination of the in situ formed allyl palladium complex, and further tautomerization or intramolecular aldol reaction. From the reaction of allenols bearing a substituent at the internal position of the allenic unit, on the other hand, diversely substituted 2-(furan-3-yl)acetamides were formed through a cascade process combining carbonylation of aryl iodide, acylation, and carbonylation of allenol followed by intramolecular condensation and amination by tertiary amine featuring an oxidant-free C−N bond cleavage.
Oxoammonium salt-promoted diverse functionalization of saturated cyclic amines with different dinucleophiles under mild conditions is presented. To be specific, when thiocyanate was used as 1,3-dinucleophile, hexahydrothiazolo[4,5-b]pyridin-2(3H)-ones were formed via the...
A convenient protocol for the synthesis of α-substituted-β-oxo azaheterocycles through oxoammonium salt-promoted cascade reaction of saturated cyclic amines with different nucleophiles based on β-oxo cyclic iminium ion intermediates has been...
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