Iodine-mediated regioselective guanylation-amination of propargylamines towards the synthesis of diversely substituted 2-aminoimidazoles

A diversity-oriented approach for the synthesis of 2-aminoimidazoles is presented.

Iodine-induced synthesis of sulfonate esters from sodium sulfinates and phenols under mild conditions

A facile and highly efficient method for the synthesis of sulfonate esters mediated by iodine at room temperature has been developed, without transition metal catalysts and oxidants.

A general, simple and green process to access pyrrolo[2,1-a]isoquinolines using a KI/TBHP catalytic system

A novel KI/TBHP-catalyzed 1,3-dipolar cycloaddition/oxidation/aromatization cascade reaction provided a general, efficient and green access to biologically important pyrrolo[2,1-a]isoquinolines.

An expeditious iodine-catalyzed synthesis of 3-pyrrole-substituted 2-azetidinones

2-Azetidinones and pyrroles are two highly important classes of molecules in organic and medicinal chemistry. A green and practical method for the synthesis of 3-pyrrole-substituted 2-azetidinones using catalytic amounts of molecular iodine under microwave irradiation has been developed. Following this method, a series of 3-pyrrole- substituted 2-azetidinones have been synthesized with a variety of substituents at N-1 and at C-4. The procedure is equally effective for mono- as well as polyaromatic groups at the N-1 position of the 2-azetidinone ring. The C-4 substituent has no influence either on the yield or the rate of the reaction. Optically pure 3-pyrrole-substituted 2-azetidinones have also been synthesized following this methodology. No deprotection/rearrangement has been identified in this process, even with highly acid sensitive group-containing substrates. A plausible mechanistic pathway has also been suggested based on the evidence obtained from ¹H-NMR spectroscopy. The extreme rapidity with excellent reaction yields is believed to be the result of a synergistic effect of the Lewis acid catalyst (molecular iodine) and microwave irradiation.

Regio- and diastereoselective synthesis of β-lactam-triazole hybrids via Passerini/CuAAC sequence

Passerini (P-3CR) and Passerini-Smiles reactions were investigated in azetidine-2,3-diones, affording the corresponding 3,3-disubstituted-β-lactams with complete diastereoselectivity in high yields. The study has been carried out using different isocyanides, carboxylic acids, and phenols showing the scope of both reactions. In addition, the regioselective synthesis of highly functionalized β-lactam-triazole hybrids has been developed via a Passerini/CuAAC sequence. Interestingly, the use of dialkynes/diazides or trialkynes/triazides as linkers in the CuAAC step has allowed the synthesis of C(2) and C(3) symmetric β-lactam-triazole hybrids, respectively.

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis

The interplay between metals and N-heterocyclic carbenes (NHCs) has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable scaffolds in heterocyclic chemistry. This Commentary will briefly highlight the concept of N-heterocyclic carbene/Brønsted acid cooperative catalysis as a new and powerful methodology in organic chemistry.