Pd(II)-catalyzed hydroarylations/hydroalkenylations of terminal alkynes: regioselective synthesis of allylic, homoallylic, and 1,3-diene systems

A Pd-catalyzed regioselective hydroarylation of terminal alkynes containing a heteroatom has been developed via carbopalladation for the synthesis of allylic ethers, amines, and homoallylic alcohols. Moreover, hydroalkenylation of alkynes produces a variety of stereodefined 1,4-dienes with high regioselectivity. The important features of the present protocol are that it is highly regioselective, operationally rapid, and scalable with a huge substrate scope using only 3 mol% of PdCl2(PPh3)2 catalyst in the presence of a mild base KOAc.

Catalytic Domino Three-Component Synthesis of Functionalized Heterocycles from Carbon Dioxide

A catalytic domino, three-component reaction has been developed for the transformation of carbon dioxide into functionalized six-membered cyclic carbonates. The catalytic process combines an initial carboxylative cyclization of β-epoxy alcohols followed by an oxa-Michael reaction affording an unparalleled scope of heterocyclic structures. The wide range of functional groups, including free-alcohols, empowers the access to a range of products including C11-oxo-based bicyclic heterocycles. The versatility of these functionalized carbonates is further complemented by a series of synthetic diversifications. Control experiments are consistent with the first step of this domino process being promoted by a binary Lewis acid/base catalyst, while the second stage only requires catalytic base.

Co(III)-Catalyzed three-component assembling of N-(2-pyrimidyl) indoles with dienes and formaldehyde

A highly regio- and chemoselective three-component assembling of N-pyrimidyl indoles with dienes and formaldehyde in the presence of a Co(III) catalyst was demonstrated. The scope of the reaction was investigated with a variety of indole derivatives to synthesize substituted homoallylic alcohols. Both butadiene and isoprene units were compatible with the reaction. To understand the reaction mechanism, various investigations were carried out, and suggested the plausibility of a reaction mechanism involving C-H bond activation as a key step.

Visible-Light-Induced Oxyalkylation of 1,2,4-Triazine-3,5(2H, 4H)-diones with Ethers via Oxidative Cross-Dehydrogenative Coupling

An efficient and convenient method to synthesize 6-oxyalkylated 1,2,4-triazine-3,5(2H, 4H)-diones has been developed via visible-light-induced cross-dehydrogenative coupling reaction between 1,2,4-triazine-3,5(2H, 4H)-diones and ethers with a wide range of functional group tolerance. The present transformation employs the cheap and low-toxic 2-tert-butylanthraquinone as a metal-free photocatalyst and air as a green oxidant at room temperature. Moreover, this reaction can also be driven by sunlight as a clean energy resource. The synthetic utility of this method is further demonstrated by gram-scale reaction and application in the preparation of key intermediates of bioactive molecules.

Rh(iii)-Catalyzed C–H allylation/annulative Markovnikov addition with 5-methylene-1,3-dioxan-2-one: formation of isoquinolinones containing a C3 quaternary centre

Rh(iii)-Catalyzed C–H allylation/annulative Markovnikov addition reaction was disclosed, offering isoquinolinones containing a C3 quaternary centre. By using this method as the key step, the US28 inverse agonist analogs were synthesized.