Stereochemistry of the generation of the ethyl group in bacteriochlorophyll a biosynthesis
Abstract
It is shown that the C-8 ethyl group of bacteriochlorophyll a(5) is formed by the addition of hydrogen to C-81 from the si-face of the corresponding double bond [4; Δ(81,82)]; this observation, when taken in conjunction with the previous finding regarding the stereochemistry of hydrogen addition to C-82, reveals that the overall saturation process occurs via the formal trans-addition.