Natural-product chemistry — IUPAC Division III organic chemistry at the secondary-metabolite / biosynthetic-pathway grain. Foundations: (1) The isoprene rule (Ruzicka 1921 / 1953, 'biogenetic isoprene rule'): all terpenes are built by…
natural-product-chemistry
Isoprene rule: terpene C-counts are exact multiples of 5 (C5n)
Ruzicka's biogenetic isoprene rule (1921, formalised 1953): all terpenes are biosynthesised by head-to-tail coupling of C₅ isoprene units…
Polyketide biogenesis: acetate C₂ head-to-tail via PKS; C1/C2 parity
Polyketide biogenesis (Birch 1953, Staunton & Weissman 2001). Polyketide synthases (PKS) catalyse the iterative condensation of acetyl-CoA…
Baldwin's rules: 20 favored / 10 disfavored of 30 (n, mode, hyb) triples
Baldwin's rules (J. E. Baldwin, J. Chem. Soc. Chem. Commun. 1976, 734): empirical stereo-electronic preferences for ring-closure reactions,…
Terpene C-counts sum 10+15+20+25+30+40 = 140 = 5·28
Sympy-exact witness of the isoprene-rule arithmetic: the total carbon count across the canonical terpene classes (monoterpene C₁₀ through…
Polyketide n=5 parity: C1-count = C2-count = 5; Σ (-1)^(k+1) = 0
Sympy-exact witness of the polyketide C1/C2 parity identity on an n = 5 acetate-unit chain (2n = 10 carbons total). Setup: even positions…
Baldwin enumeration: |favored|=20, |disfavored|=10, total=30 = 5·2·3
Sympy-exact witness of the Baldwin-rules enumeration. Setup: build the full Cartesian product {3,4,5,6,7} × {exo, endo} × {tet, trig, dig}…