Photochemistry of three N-acetoacetyl amino acid methyl esters: Structure elucidation of the radiation products by gas chromatography mass spectrometry

The photochemistry of three N-acetoacetyl alpha-amino acid (valine, tert-le ucine, isoleucine) methyl esters was investigated. The products after UV ir radiation in acetonitrile at 300 nm (direct excitation) were analyzed by ga s chromatography coupled with chemical ionization mass spectrometry. In all cases a complex product mixture was found as the result of the n pi* excit ation of the substrates. The major reaction paths were Norrish type I react ions and hydrogen atom abstractions with concomitant radical cleavage and r adical recombination steps. (C) 1998 John Wiley & Sons, Ltd.