Abstract Vitamin K 2 (x) mp 58–59º, isolated by N OLL from M. tuberculosis, proved to be 2- methyl-3-solanesyl-1, 4-naphthoquinone having a side-chain of 45 C-atoms. This vitamin K 2 (45) was synthesized from menadiol and solanesol. The next higher isoprenologue, ...