Gary B. Quistad

Hematinic acid and propentdyopents from bilirubin photo-oxidation in vitro.

The structures of the photo-oxidation products [ 11 of bilirubin 1x0~ (1) are of special interest to those concerned with a widely used clinic phototherapy for hyperbilirubinemia (jaundice) in the newborn [2. 31. Untreated neonatal jaundice may lead to cerebral palsy or even death. In the phototherapy treatment. lipophilic bilirubin is removed by its conversion to excretable, water soluble substances [4] whose structures and toxicities are largely unknown as yet [ 1. 51. Considerable data have accrued on the visible-ultraviolet spectral changes accompanying the photo-destruction of 1. and paper chromatographic separations of the photo-products have been achieved [3. 5, 61 with an indication of possible structures [5-71. Very recently a methanol propentdyopent adduct was determined to be a photoproduct. but the precise structure was not proved unambiguously [7]. McDonagh [8] has shown that 1 is a singlet oxygen (‘0,) (91 sensitizer; apparently it sensitizes its own photo-destruction. In our earlier work [l] we first isolated and proved that methylvinylmaleimide is an irz vitro photo-oxidation product of 1. In the following we report on the first isolation and positive structure identification of hematinic acid (2) and two isomeric propentdyopent derivatives (3 and 4) as important products from in vitro photooxidation. 2. Materials and methods

Methylvinylmaleimide from Bilirubin Photooxidation

Irradiation of an oxygenated methanolic solution of bilirubin IXα in the absence of known singlet oxygen sensitizers gave methylvinylmaleimide among other products.

HYDROGEN REARRANGEMENTS IN THE MASS SPECTRA OF ALKYLBENZENES.

By means of extensive deuterium labeling, the γ-carbon has been shown to be the principal site of transferred hydrogen (deuterium) regardless whether the hydrogen (deuterium) is primary, secondary, or tertiary. Although a significant transfer is also observed from the β, δ, ε, and more remote (to θ) carbons of the alkyl chain, such transfer is not attended by C–C cleavage (fragmentation) and is interpreted as an exchange between the aromatic ring (ortho-hydrogen atoms) and the alkyl chain hydrogen atoms (deuterium atoms). The data herein also set small upper limits 011 the formation of m/e 91 (C7H7+) from m/e 92 (C7Hs+−) at both high and low ionizing voltages as well as in long and short alkyl chains.

Pyrrole photo-oxidation. The direct formation of maleimides

Photo-oxidation of 3,4-diethylpyrrole in methanol gives mainly diethylmaleimide and 3,4-diethyl-5-methoxy-Δ3-pyrrolin-2-one; photolysis of pyrrole under similar conditions gives mainly 5-methoxy-Δ3-pyrrolin-2-one with a low yield of maleimide, but in aqueous solution, only 5-hydroxy-Δ3-pyrrolin-2-one and no maleimide is formed.