Synthesis of Cypridina Luciferin and Related Compounds. III. : Synthesis of Cypridina Luciferin

Abstract

Synthetic Cypridina etioluciferamine (I) described in the previous paper, was transformed in a good yield to Cypridina etioluciferin (II) by condensation with S-ethylisothiourea. II was identical with the natural Cypridina etioluciferin in every respects. II was successfully converted to Cypridina luciferin (III) by using the following procedures ; the etioluciferin (II) was treated with D-2-oxo-3-methylvaleric acid (IV) in ethanol, reduced by aluminum amalgam or by catalytic hydrogenation, and finally treated with DCC in ethanol under argon at 4°. The product, Cypridina luciferin (III), was purified through an alumina column and isolated as its hydrobromide. The synthesized luciferin (III) hydrobromide was found to be identical with the natural luciferin hydrobromide in every respects (biological activity, UV spectrum, IR spectrum, mp, mixed mp, paper chromatography).