Nayif Sohail Alhomoud
Dhahran Ahliyya School, Dammam, Eastern, SAUDI ARABIA
The Suzuki-Mayura cross-coupling reaction is one of the most powerful and versatile methods to form C-C and C-X bonds. However, this reaction typically employs organic solvents, which pose risks to health, safety and environment. The purpose of this project is to maximize the sustainability and efficiency of this reaction. Towards a "green chemistry†approach, five biogenic palladium catalysts were synthesized. The novelty in the catalysts is the ligands applied, which were synthesized from five different amino acids: alanine (a), valine (b), leucine (c), isoleucine (d), and methionine (e). The activity of these catalysts was investigated for Suzuki-Mayura cross-coupling reaction in aqueous medium. To synthesize the catalysts, condensation reaction was applied to amino acids with glyoxal and formaldehyde in water to form imadazolium salts (1a–1e). The imadazolium salts were esterified with trimethylsilyl chloride in methanol (2a–2e). The esterified compounds reacted with silver oxide to form silver carbene complexes (3a–3e), which underwent transmetallation with PdCl2(CH3CN)2 to obtain the desired chiral palladium catalyzed complexes (4a–4e). The catalyzed complexes were fully characterized by NMR. They were active in Suzuki-Mayura cross-coupling reaction in water under microwave conditions, with complex (4a) reaching outstanding yields of 99% based on the GC Analysis with excellent activities characterized by TOFs > 750 s-1 and TONs > 1`000`000. This research can lead to potentially beneficial applications including sustainable synthesis of drugs and organic light emitting diodes. To broaden the scope of our catalysts, further research includes carrying out asymmetric catalysis using our chiral catalyst precursors. Awards won at the 2012 ISEF Fourth Award of $500 - Chemistry - Presented by Intel