A Mild and Efficient Method to Functionalize Azines (Quinoline,Isoquinoline, and Phenanthridine) Using Acetylenic Esters and Heterocyclic NH or 1,3‐Dicarbonyl Compounds

One‐pot reactions involving azines (quinoline, isoquinoline, and phenanthridine), with acetylenic esters in the presence of heterocyclic NH compounds (benzotriazole, 2‐methylbenzimidazole, 2‐benzoxazolinone, 6‐chlorobenzoxazolinone, maleimide, indole, and 2‐methylindole) or 1,3‐dicarbonyl compound such as 5,5‐dimethyl‐1,3‐cyclohexadione, are described. The reactions proceeded smoothly at RT, and with excellent yields. The structures of the synthesized compounds have been characterized by the elemental analyses and spectral studies.     

Lanthanide Triflate Catalyzed One-Pot Synthesis of Dihydropyrimidin-2(1H)-thiones by a Three-Component of 1,3-Dicarbonyl Compounds,Aldehydes, and Thiourea Using a Solvent-Free Biginelli Condensation

Abstract

Novel one-pot Biginelli-type reaction has been developed. Aromatic and aliphatic aldehydes with β-dicarbonyl compounds and thiourea in the presence of catalytic amount 5 mol% of Yb(OTf)₃ at 100° C for 60–90 min under solvent-free conditions proceeded smoothly to afford corresponding dihydropyrimidin-thiones. The yields of the classical Biginelli reaction can be increased from 20–50% to 81–91% while the reaction time was shortened from 18–48 h to 60–90 min. In addition the catalyst can be easily recovered and reused.     

An Approach to the Synthesis of Spiro[indene‐pyridoisoquinoline] Derivatives via 1,4‐Dipolar Cycloaddition of Isoquinoline and Acetylene Esters,and (1,3‐Dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile

A concise and efficient approach to the spiro‐tetrahydroisoquinoline derivatives has been developed by 1,4‐dipolar cycloaddition of zwitterions resulting from isoquinoline and acetylene esters and (1,3‐dihydro‐1,3‐dioxo‐2H‐inden‐2‐ylidene)malononitrile in MeCN at room temperature. The significance of this method lies in good yields and ease of product purification, and no inert atmosphere is required. The structures of the products were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme).