Efficient Synthesis of Fluorescent Coumarins and Phosphorous-Containing Coumarin-Type Heterocycles via Palladium Catalyzed Cross-Coupling Reactions

Abstract

Quantum-chemical calculations on the spectral properties of some aryl substituted 3-phosphonocoumarins were performed, and the effect of the substituents in the aryl moiety was evaluated. The structures possessing promising fluorescent properties were successfully synthesized via Suzuki and Sonogashira cross-coupling. The synthetic protocol was also applied for the phosphorous chemoisomer of 3-phosphonocoumarin, 1,2-benzoxaphosphorin, and their carboxylate analogues. The optical properties of the arylated and alkynylated products were experimentally determined. The obtained quantum-chemical and experimental results give the possibility for a fine tuning of the optical properties of phosphorous-containing coumarin systems by altering the substituent at its C-6 position.

An enhanced stereoselective synthesis of α,β-unsaturated esters through the Horner–Wadsworth–Emmons reaction in deep eutectic solvents

“…This stands in contrast to other multi-step synthetic methodologies relying on cross-coupling reactions. 26…”

“…This stands in contrast to other multi-step synthetic methodologies relying on cross-coupling reactions. 26 Aldehydes with carbonyl-containing electron-withdrawing groups (COOH, CONEt 2 , COOMe; entries 18-20, Table 2) and an electron-donating group (-NMe 2 ) on the aromatic ring (entry 21, Table 2) afforded cinnamates 3k-n in fair to good yields (40-68%), but with high stereoselectivities (E/Z up to 99 : 1) in all cases.…”

Transition-Metal-Catalyzed C–H Activation Reactions for the Creation and Modification of Organic Fluorophores

“…Palladium-catalyzed cross-coupling reactions have been extensively employed in material chemistry in the synthesis of a wide spectrum of fluorescent molecules. [30][31][32][52][53][54][55][56][57][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] However, the drawback is the requirement for pre-functionalized starting materials which usually are aryl halides or pseudohalides. 76 Of the aryl halides, aryl chlorides are usually the cheapest and most easily accessible, but they are, at times, poorly active in palladium-catalyzed cross-coupling reactions due to their slower rate of oxidative addition (Scheme 16).…”