A monoclinic form of dendocarbin A: a borderline case of one‐dimensional isostructural polymorphism

The title compound, dendocarbin A systematic name: (1R,5aS,9aS,9bR)‐1‐hydroxy‐6,6,9a‐trimethyldodecahydronaphtho1,2‐c]furan‐3‐one], C₁₅H₂₂O₃, is a sesquiterpene lactone isolated from Drimys winteri var chilensis. The monoclinic phase described herein displays an identical molecular structure to the orthorhombic phase that we reported previously Paz Robles et al. (2014). Acta Cryst. C 70 , 1007–1010], while varying significantly in chain pitch, and can thus be considered as a borderline case of one‐dimensional isostructural polymorphism.