Abstract Two new and six known aliphatic aldehydes have been isolated from the roots of Cirsium dipsacolepis, viz. 7-octenal,(2E)-2, 8-nonadienal,(2E)-2, 9-decadienal,(2E)-2, 10- undecadienal,(2E, 4E)-2, 4, 10-undecatrienal,(2E, 4E)-2, 4, 11-dodecatrienal,(2Z, 4Z)-2, 4, 11-dodecatrienal and (2E, 4Z)-2, 4, 11-dodecatrienal. The aldehydes were identified and synthesized stereoselectively from alkane-α, ω-diynes.
