Wallach isoprene-rule classification framework: terpene C-count is a fixed integer multiple of 5 (n·C5)

Wallach 1887 isoprene rule / Ruzicka 1953 biogenetic isoprene rule: all terpenes are biosynthetically constructed from isoprene-unit (C5) precursors (DMAPP and IPP) in a strict head-to-tail cascade, so every terpene's carbon count is an…