Aerobic oxidation of aldehydes to acids with N-hydroxyphthalimide derivatives

Structure-Activity Relationship Study of N-Hydroxyphtalimide Derivatives for the Detection of Amines during Fmoc-Solid-Phase Peptide Synthesis

Previously, we developed a method for the detection of unprotected amino groups based on their reversible reaction with N-hydroxyphthalimide (NHPI) to form intensely colored products, which can be useful when conducting solid-phase peptide synthesis. Here, we describe a structure-activity relationship study of NHPI derivatives to identify the derivative best suited for this method using a spectrophotometer toward the estimation of chemical yields. We found that the products resulting from the reaction of the derivative with an unprotected amino group were only intensely colored if the structure of the derivative incorporated an NHPI framework. We also prepared five peptides, including those containing N-methyl and D-amino acid, and Pro residues, using our reversible detection method to detect unprotected amino groups. The mechanism of the detection reaction was also studied by the structural analysis of the NHPI (1) and diisopropylamine complex and concluded to entail salt formation between the N-hydroxy group and amine.

Selective oxidation of aldehydes by oxygen over macroporous alkaline resin

In this reaction, the oxidation of aldehydes is selectively catalyzed by basic resin D201-OH for the first time. Moreover, mild and high-yield oxidation of aldehydes can be achieved without any cocatalyst.