Copper/silver-cocatalyzed Conia-ene reaction of linear beta-alkynic beta-ketoesters

A novel and general copper/silver catalytic system has been developed for the Conia-ene intramolecular reaction of linear beta-alkynic beta-ketoesters. In the presence of (CuOTf)2.C6H6 and AgSbF6 (or AgOAc), a variety of the linear beta-alkynic beta-ketoesters selectively underwent the Conia-ene intramolecular reaction in moderate to good yields.     

Palladium-catalyzed carbonylative annulation reaction of 2-(1-alkynyl)benzenamines: selective synthesis of 3-(halomethylene)indolin-2-ones

A novel and selective palladium-catalyzed carbonylative annulation process for the synthesis of 3-(halomethylene)indolin-2-ones was demonstrated. In the presence of PdX2 and CuX2, 3-(halomethylene)indolin-2-ones were selectively obtained from the carbonylative annulations of 2-(1-alkynyl)benzenamines with CO in moderate to good yields.     

Iron-mediated [3 + 2] or [3 + 3] annulation of 2-(2-(ethynyl)phenoxy)-1-arylethanones: selective synthesis of indeno[1,2-c]chromenes and 5H-naphtho[1,2-c]chromenes

An iron-mediated tandem annulation strategy has been developed for the synthesis of numerous functional indeno[1,2-c]chromenes and 5H-naphtho[1,2-c]chromenes. This work is the first to disclose an iron-mediated method through sequential electrophilic addition of a ketone to an alkyne and annulation tandem reaction. Importantly, a halide is introduced into the products by a ring-opening process among the annulation of alkynylcyclopropanes, which makes the methodology more attractive for organic synthesis.     

Palladium-catalyzed selective heck-type diarylation of allylic esters with aryl halides involving a β-OAc elimination process

Palladium-catalyzed selective Heck-type diarylation of allylic esters with aryl halides has been developed. Allylic esters are reacted with aryl iodides to provide the corresponding 1,3-diaryl propenes through a β-OAc elimination process. It is noteworthy that the methodology can be applied in constructing the indole and benzofuran skeletons.     

CuI/I2-promoted electrophilic tandem cyclization of 2-ethynylbenzaldehydes with ortho-benzenediamines: synthesis of iodoisoquinoline-fused benzimidazoles

An efficient tandem route to the synthesis of iodoisoquinoline-fused benzimidazole derivatives including an iodocyclization strategy has been developed. In the presence of CuI, a variety of 2-ethynylbenzaldehydes underwent the tandem reaction with benzenediamines and iodine to afford the corresponding iodoisoquinoline-fused benzimidazoles in moderate to good yields.     

Synthesis of 3-(aminomethylene)-2-oxoindolines by palladium-catalyzed annulation of 3-chloro-2-iodo-N-arylacrylamides with amides or amines

A new palladium-catalyzed C-H bond activation-annulation-amination tandem method was presented for selectively synthesizing 3-(aminomethylene)-2-oxoindolines. In the presence of Pd(dba)(2), xantphos (L8), AgOAc and Na(2)CO(3), a variety of 3-chloro-2-iodo-N-arylacrylamides underwent the reaction with amides or amines to afford the corresponding 3-(aminomethylene)-2-oxoindolines in moderate to good yields.     

Intramolecular ipso-halocyclization of 4-(p-unsubstituted-aryl)-1-alkynes leading to spiro[4,5]trienones: scope, application, and mechanistic investigations

A new, general method for the synthesis of spiro[4,5]trienones is described by the intramolecular ipso-halocyclization of 4-(p-unsubstituted-aryl)-1-alkynes. In the presence of halide electrophiles, a variety of 4-(p-unsubstituted-aryl)-1-alkynes underwent the intramolecular ipso-halocyclization with water smoothly, affording the corresponding halo-substituted spiro[4,5]trienones in moderate to good yields. The obtained spiro[4,5]trienones can be applied in constructing the azaquaternary tricyclic skeleton via Pd-catalyzed Heck reaction. Notably, the prepared spiro[4,5]trienones and azaquaternary tricycles are of importance in the areas of pharmaceuticals and agrochemicals. The mechanism of the intramolecular ipso-halocyclization reaction is also discussed according to the (18)O-labeling experiments and DFT calculations.     

Copper-Catalyzed CH Oxidation/Cross-Coupling of α-Amino Carbonyl Compounds

Keeping options open: The new and mild title reaction involving indoles selectively furnishes 1 and 2 with the aid of tert-butyl hydroperoxide (TBHP). The method represents the first example of a copper-catalyzed α?arylation of α-amino carbonyl substrates leading to α-aryl α-imino and α-aryl α-oxo carbonyl compounds using a C?H oxidation strategy.     

Synthesis of 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls by palladium-catalyzed Ullmann reaction

A novel palladium-catalyzed Ullmann protocol is described for the synthesis of 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls. In the presence of Pd(OAc)₂ and KOAc, intramolecular or intermolecular Ullmann coupling of aryl halides proceeds efficiently under ligand-free and aerobic conditions to afford the corresponding 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls in moderate to excellent yields.