Asymmetric Phase-Transfer Reaction

Phase-transfer alkylations e.g. with the chiral Maruoka catalyst result in unique α-mono substituted and α,α-disubstituted unnatural amino acids. Typically such building blocks implemented in peptides increase the chemical and metabolic stability of their peptides and restrict the conformational freedom of side chains in amino acids.

Though rather costly in gram scale synthesis, this process opens new avenues for designing and economic production of appropriate building blocks in multi-kg and bulk scale. Conventional amino acids can be produced via such stereoselective alkylation of glycine or alanine without any use of metal, hence a safe and environmentally friendly technology.

References:
Tanaka, M. Chem. Pharm. Bull. 2007; 55: 349-358.
Maruoka M. et al; J. Am. Chem. Soc. 2003; 125: 5139-5151. Maruoka M. et al; Tetrahedron Lett. 2000; 41: 8339-8342.
Maruoka M. et al; Synthesis 2001; 1716-17148. Maruoka M. et al; Process Research & Development 2008; 12: 679-687.
Patents: USP (6,340,753; 6,441,231; 7,928,224; 8,252,952) JP (4,217,085; 4,502,293; 4,605,606; 5,106,562; 5,108,777; 5,108,888)
SG 139,249; IN 252,017; CN ZL200680027800.6