Palladium-Catalyzed Chemoselective Oxidative Addition of Allyloxy-Tethered Aryl Iodides: Synthesis of Medium-Sized Rings and Mechanistic Studies

Access to 5- to 14-Membered N-Heterocycles by Alkylamination of 1,3-Dienes via Palladium Catalysis

Medium-sized rings show great potential in medicinal chemistry but are difficult to achieve via direct cyclization reaction. We herein report a versatile and mild photocatalytic approach for synthesis of medium- and large-sized vinyl N-heterocycles by radical-mediated cyclization of sulfonamides with pendant 1,3-dienes. The reaction involves the generation of radicals from alkyl halides and cyclization of π-allylpalladium species. This method could serve as a versatile platform for the construction of N-heterocycles with medium- and large-sized rings via Pd catalysis.

Organocatalyzed enantio- and diastereoselective isomerization of prochiral 1,3-cyclohexanediones into nonalactones bearing distant stereocenters

The lactonization of 2-(2-nitrophenyl)-1,3-cyclohexanediones containing an alcohol side chain and up to three distant prochiral elements is reported by isomerization under the mediation of simple organocatalysts such as quinidine. Through a process of ring expansion, strained nonalactones and decalactone are produced with up to three stereocenters in high er and dr (up to 99 : 1). Distant groups, including alkyl, aryl, carboxylate and carboxamide moieties, were examined.

Synthesis of Ladder-Type 9,9'-Bifluorenylidene-Based Conjugated Oligomers via a Pd-Catalyzed Tandem Suzuki Coupling/Heck Cyclization Approach

For new ladder-type oligomers and polymers with versatile and robust synthetic strategies, in this study, four fully conjugated ladder-type overcrowded 9,9'-bifluorenylidene-based compounds and oligomers (BFY1, BFY2, BFY3, and BFY4) were synthesized via a Pd-catalyzed tandem Suzuki coupling/Heck cyclization reaction. By monomer screening and route optimization, the target products were obtained in high yields and characterized by ¹H and ¹³C NMR spectroscopy and high resolution mass spectroscopy.

Regioselective and stereospecific synthesis of functionalized 3,4-dihydro-2H-1,4-thiazines by catalyst-free [3 + 3] annulation of pyridinium 1,4-zwitterionic thiolates and aziridines

An efficient route to 3,4-dihydro-2H-1,4-thiazines was developed though [3 + 3] annulation of pyridinium 1,4-zwitterionic thiolates and aziridines under catalyst-free conditions.

Palladium-Catalyzed Chemoselective Oxidative Addition of Allyloxy-Tethered Aryl Iodides: Synthesis of Medium-Sized Rings and Mechanistic Studies

This Letter describes a Pd-catalyzed Tsuji-Trost-type/Heck reaction with allyloxy-tethered aryl iodides and aziridines. The strategy provides efficient access to benzannulated medium-sized rings via intermolecular cyclization. The substrate aryl iodide has two oxidative addition sites, that is, the aromatic C-I bond and the allyl-oxygen bond. The chemoselective oxidative addition of allyl-oxygen bonds is favored, followed by the activation of aromatic C-I bonds. Aziridine plays a key role. Mechanistic studies shed light on the reaction pathway.