The asymmetric synthesis of hydratropic acid and amino-acids by homogeneous catalytic hydrogenation

Abstract

A new optically active diphosphine-rhodium(1) catalytic system has been used in several asymmetric reductions giving optical yields of up to 72%.

Pioneering Perspectives on Asymmetric Hydrogenation

“…5 This modest result, fortunately coupled with easy separations, enabled the commercial production of the anti-Parkinsonian drug L-DOPA at Monsanto, where AH was the key step. 1 The field really got underway with the discovery of C 2 -chiral DIOP by Dang and Kagan, 6 followed by Monsanto's improved C 2 bisphosphine Di-PAMP. 1 This success generated a lot of interest, and for the next decade, a considerable number of efficient bisphosphine ligands of wildly different structures were discovered, useful only on enamide precursors of R-amino acids and closely related substrates and little else.…”

Ligand Design for Catalytic Asymmetric Reduction

“…DIOP developed by Kagan is the origin of this type of chiral ligand. 22 Figure 1.4 illustrates the chiral template created by an (R)-BINAP-transition metal complex. [18][19][20][21] The naphthalene rings are omitted in the side view for clarity.…”

Asymmetric Hydrogenation

“…In 1971, Kagan et al synthesized a chelating diphosphine ligand with two phenyl groups on each of the two phosphorus atoms [4]. The ligand, 4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolane (DIOP), is the first example of a C2-symmetric phosphine ligand.…”