Diastereoselective Synthesis of 3,4-Dihydropyran-3-carboxamides with in Vitro Anti-inflammatory Activity

Diastereomerically pure rarely functionalized alkenoyl dihydropyrans, 1,6-diketones, and cyclopentanes from acetylene gas and ketones

Alkenoyl dihydropyrans stereoselectively assembled from acetylene gas, ketones and aldehydes in two steps are diastereoselectively transformed into difficult-to-access, rarely functionalized 1,6-diketones and cyclopentanes.

Access to molecular complexity. Multicomponent reactions involving five or more components

The evaluation of the significance of a chemical transformation addresses many factors, including such important characteristics as the number of chemical bonds formed in one step, the reaction time, labour intensity, the cost of reactants and catalysts and so on. The amount of waste produced in the reaction has also gained increasing importance in recent years. Multicomponent reactions (MCRs) occupy a special place as a synthetic tool in modern organic chemistry. These reactions allow the synthesis of target products with complex structures, minimizing labour costs. This review summarizes the literature on multicomponent reactions involving five or more components. The data in the review are classified according to the number of reactants participating in the reaction and the types of reactions. It is worth noting that in some cases, these transformations can be a part of a domino process, making this classification difficult, if not impossible. The structural diversity of the reaction products greatly increases with increasing number of components involved in the MCR, which becomes virtually unlimited when using combinations of MCRs. This review highlights the main trends of past decades in the field of MCRs. The last two decades have witnessed an explosive growth in the number of publications in this area of chemistry.

The bibliography includes 309 references.

A novel substrate directed multicomponent reaction for the syntheses of tetrahydro-spiro[pyrazolo[4,3-f]quinoline]-8,5'-pyrimidines and tetrahydro-pyrazolo[4,3-f]pyrimido[4,5-b]quinolines via selective multiple C-C bond formation under metal-free conditions

A versatile and substrate oriented multicomponent reaction for the syntheses of novel highly diastereoselective tetrahydro-1'H-spiro[pyrazolo[4,3-f]quinoline-8,5'-pyrimidine]-2',4',6'(3'H)-triones (d.r. up to 20 : 1 (syn : anti)) and tetrahydro-8H-pyrazolo[4,3-f]pyrimido[4,5-b]quinoline-8,10(9H)-diones via formation of selective multiple C-C bonds under identical reaction conditions (viz. ethanol as a reaction medium and deep eutectic mixture as a catalyst) is demonstrated. Both approaches involve mild reaction conditions, use of non-hazardous solvents, and facilitate good to excellent reaction yields of the target compounds.

"On water" palladium catalyzed diastereoselective boronic acid addition to structurally diverse cyclopropane nitriles

An efficient palladium catalyzed diastereoselective addition of arylboronic acids to complex spirocyclopropyl dinitriles is developed in the presence of a catalytic amount of 4-dodecylbenzenesulphonic acid (DBSA) as a Brønsted acid surfactant in aqueous media. The protocol is also found to be highly effective when different types of nitrile compounds and organo-boron compounds are used. The overall reaction has been found to be very cost efficient since it requires low catalyst loading, mild thermal energy and short reaction time. Wide substrate scope, operational simplicity, good to excellent product yield, and use of green solvents make the reaction a practical route to transform nitrile into a keto functionality in biorelevant heterocyclic scaffolds. The scale-up synthesis of the target scaffolds can also be achieved with ease which also signifies the practicability of this protocol.