Retention of configuration in photolytic decarboxylation of peresters to form chiral acetals and ethers.

Peresters generate ethers in good yields when photolyzed in the absence of solvent using short wavelength UV light. At -78 degrees C or below, the process proceeds predominantly with retention of configuration at the site adjacent to the carbonyl where the decarboxylation occurs, but increase in temperature results in loss of stereochemical control. Chiral acyclic acetals can be prepared using precursors derived from tartaric or malic acids.

Photolysis of diacyl peroxides: a radical-based approach for the synthesis of functionalized amino acids.

[reaction: see text] Photolysis of the amino acid derived symmetrical and unsymmetrical diacyl peroxides at 254 nm at low temperature (-78 to -196 degrees C) generates various bis(amino acids) in a concise manner and with orthogonal protection. The methodology was applied to the synthesis of (4R)-5-propyl-L-leucine (PrLeu), a component of HUN-7293.