Carbon‐13 NMR lanthanide induced shifts and T₁ studies of the conformation of friedelin

By measuring the shifts of the ¹³C NMR signals of 29 carbons of friedelin, induced by the lanthanide shift reagent Pr(fod)₃, and using a computer program, it is shown that friedelin exists in a chair‐chair‐chair‐twist boat‐boat conformation in solution. Lanthanide metal binds exclusively to one site on the carbonyl group of friedelin, away from the nearest methyl group. ¹³C T₁ data are consistent with the suggested conformation of friedelin.