Expanding the Scope of Lewis Acid Catalysis in Water:  Remarkable Ligand Acceleration of Aqueous Ytterbium Triflate Catalyzed Michael Addition Reactions

Abstract

[reaction: see text] Significant rate acceleration of metal-catalyzed Michael addition reactions in water was observed upon addition of small, dibasic ligands. Ytterbium triflate and TMEDA was the most effective combination leading to a nearly 20-fold faster reaction than in the absence of ligand.

α‐Amino Acid Induced Rate Acceleration in Aqueous Biphasic Lewis Acid Catalyzed Michael Addition Reactions

“…[5] Recent significant advances have been the use of solid-phase Lewis acid catalysis [6] and our own discovery that small 1,2-dibasic ligands, N,N,N',N'-tetramethylethylenediamine (tmeda) in particular, can have a remarkable effect on aqueous Michael addition reactions catalyzed by ytterbium triflate. [7] Herein we report our first results on the use of a-amino acids as rate-accelerating ligands.…”

Addition Reactions: Polar Addition

“…Ytterbium triflate and TMEDA was the most effective combination leading to a nearly 20-fold faster reaction than in the absence of ligand. 148 Asymmetric 1,4-addition of various malonates to enones has been carried out using Bu 4 N + BH 4 − in the presence of a chiral ligand, such as (R,R)- (102). The Michael ee adducts were formed in good yields (61-67%) with moderate enantioselectivity at 0 • C. 11 B NMR spectroscopy suggests that the reaction proceeds via the formation of an aminodiol borate complex.…”

“…The mechanism of enantioselective Michael addition of acetylacetone (147) to β-nitrostyrene (148), catalysed by a thiourea-based chiral bifunctional organocatalyst (149), has been investigated theoretically, using DFT calculations. A systematic ee conformational analysis was presented for the catalyst; both substrates apparently coordinate preferentially via bidentate hydrogen bonds.…”

Bimetallic Oriented (Au/Cu2O) vs. Monometallic 1.1.1 Au (0) or 2.0.0 Cu2O Graphene‐Supported Nanoplatelets as Very Efficient Catalysts for Michael and Henry Additions

“…Henry reaction is a “nitroaldol condensation” and one of the most atom‐economical C–C coupling processes , . Under classical conditions, both reactions require basic or acidic catalysts in the presence of organic solvents, and long reaction times, which may lead to environmentally hazardous residues and undesirable by‐products …”