A silver-catalyzed protocol for the synthesis of 3-(1H-isochromen)-chromones is described. The method involves an initial 6-endo-dig cyclization of o-alkynylbenzaldehydes and domino CÀ H alkylation and chromone annulation of the ohydroxyarylenaminones, which enables the installation of 1H-isochromen and chromone in a single structure. This synthetic strategy is advantageous for the excellent regioselectivity, step economy, concise one-pot methodology, gram-scale synthesis, as well as high bond-forming efficiency.
Using benzylamines as the C4 source of 1,4dihydropyridines (1,4-DHPs), a Cu-catalyzed oxidative [1 + 2 + 1 + 2] cascade cyclization for the synthesis of 1,4-DHPs was firstly developed. A broad range of easily available N,Ndimethyl enaminones and benzylamines are employed smoothly to provide a diverse range of 1,4-DHPs with high efficiency. This method is performed by a one-pot cascade C(sp 3 )À H bond functionalization/C(sp 3 )À N cleavage/cyclization strategy to form simultaneously two C(sp 3 )À C(sp 2 ) bonds, two C(sp 2 )À N bonds, and a 1,4-DHP ring.
The assembly of isocoumarins starting from easily available N,N-dimethyl enaminones and iodonium ylides via a Rh(III)-catalyzed C−H bond activation/annulation cascade reaction is herein described. This protocol proceeds under mild conditions...
An oxidative [3+2+1] cyclization of enaminones and N‐alkenyl‐2‐pyrrolidinone is described for the synthesis of 4‐alkylated 1,4‐dihydropyridines (1,4‐DHPs). By using terminal olefin as the C4 source of the 1,4‐DHP skeleton, this synthetic strategy provides a series of 1,4‐DHPs through a 1,1‐difunctionalization/cyclization process. In this protocol, two C(sp3)−C(sp2) bonds and a C(sp2)−N bond are simultaneously formed, the hydrogen source on the newly formed methyl group of the 1,4‐DHP skeleton is confirmed and a possible mechanism is proposed.
The divergent synthesis of dihydropyrimidouracil and pyrimidouracil derivatives from N‐uracil amidines and tertiaryamines by an oxidative C(sp3)−N cleavage cascade cyclization reaction is first described. This transformation enables the formation of new C(sp3)−N and C(sp2)−N bonds via the selection of different oxidation conditions. The features of this method include tunable product selectivity, excellent chemoselectivity, readily available starting materials, broad substrate scope, good tolerance of functional groups, and moderate to high yields.
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