Nano-TiCl4/SiO2: an efficient catalyst for the one-pot synthesis of highly substituted dihydro-2-oxopyrroles

Acetylenic Esters in Organic Synthesis

Activated acetylenic substrates such as acetylenic esters and alkyl propiolates are very important in organic synthesis. Due to their electron deficiency, these compounds are widely used in combinatorial and multicomponent reactions, enabling the synthesis of a large variety of novel compounds. In addition, these substrates are powerful Michael acceptors and convenient dienophiles and dipolarophiles in Diels–Alder and 1,3-dipolar cycloaddition reactions. The addition of different nucleophiles, primarily phosphorus, nitrogen or sulfur, to the triple bonds of these substrates produces key intermediates, such as Tebby and Huisgen zwitterions, which can lead to designing pathways toward the generation of spirocyclic and polycyclic compounds. This account highlights recent studies on the chemistry of acetylenic esters and their applications in organic synthesis.

1 Introduction

2 Synthesis of Acyclic and Monocyclic Compounds

3 Synthesis of Spirocyclic Compounds

4 Synthesis of Polycyclic Compounds

5 Conclusion

The development of imin-based tandem Michael-Mannich cyclocondensation through a single-electron transfer (SET)/energy transfer (EnT) pathway in the use of methylene blue (MB+) as a photo-redox catalyst

A four-component green tandem approach for the metal-free synthesis of polyfunctionalized dihydro-2-oxypyrroles was devised using the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylaes, and formaldehyde. Photo-excited state functions generated from methylene blue (MB⁺) were employed as single-electron transfer (SET) and energy transfer (EnT) catalysts at ambient temperature in an ethanol solvent, employing visible light as a renewable energy source in the air atmosphere. This study aims to increase the usage of a non-metal cationic dye that is both inexpensive and widely available. Methylene blue is photochemically produced with the least amount of a catalyst due to its high yields, energy-effectiveness, high atom economy, time-saving features of the reaction, and operational simplicity. As a result, a variety of ecological and long-term chemical features are achieved. Surprisingly, such cyclization can be done on a gram scale, implying that the process has industrial potential.

A four-component green tandem approach for the metal-free synthesis of polyfunctionalized dihydro-2-oxypyrroles was devised using the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylaes, and formaldehyde.

Multi-component synthesis of piperidines and dihydropyrrol-2-one derivatives catalyzed by a dual-functional ionic liquid

N,N,N’, N’-tetramethyl- N,N’-bis(sulfo)ethane-1,2-diaminium mesylate ([TMBSED][OMs]2) was employed for the synthesis of piperidines and dihydropyrrol-2-ones via one-pot multi-component reactions in simple and green processes. This pseudo five-component reaction of aromatic aldehydes, anilines and alkyl acetoacetates was carried out under reflux conditions in ethanol to afford substituted piperidines. Also, dihydropyrrol-2-one derivatives were synthesized by means of four-component reactions of various amines, dialkyl acetylenedicarboxylates and formaldehyde in ethanol at room temperature. The present approaches have several advantages such as good yields, easy work-ups, short reaction times, and utilize mild and clean reaction conditions.

Synthesis of highly substituted dihydro-2-oxopyrroles using Fe3O4@nano-cellulose–OPO3H as a novel bio-based magnetic nanocatalyst

A green and environmentally friendly approach for the synthesis of dihydro-2-oxopyrrole derivatives was developed using Fe₃O₄@nano-cellulose–OPO₃H as a novel bio-based magnetic nanocatalyst.