Nuclear magnetic resonance and UV spectral probe of photochemical steady states of vitamin K1

Date
1994
Authors
Gandhi, R P
Ishar, M P S
Srivastava, Rashmi
Sarin, Rita
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Abstract
Steady state photochemistry of vitamin K1 has been examined using a 1H nuclear magnetic resonance probe on solutions in CDCl3, acetone-d6, benzene-d6 and acetonitrile-d3, and a UV probe on solutions in acetone, pentane and ethanol. A rationale for formation of the major photoproduct, i.e. chromenol (1), based on electron transfer from the side-chain olefinic bond to the naphthoquinone moiety in vitamin K1, has been suggested. The new mechanistic scheme implicates, inter alia, quinone methide (6) as the precursor of 1. Attempted separation of photolysis mixture using flash chromatography has led to isolation of 9 and an oxygen adduct 10 of chromenol (1). The photoconversion of the vitamin is accelerated with catalytic amounts of triethylamine.
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Keywords
vitamin K1, nuclear magnetic, side-chain olefinic bond, naphthoquinone moiety, photolysis mixture, triethylamine
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