Tobacco Chemistry.29. (7S)-10-Oxo-4xi-methyl-7-isopropyl-5E-undecen-4-olide, a New Thunbergan-type Nor-isoprenoid isolated from Greek Nicotiana tabacum L.

The structure of a new C15-lactone, (7S)-10-oxo-4xi-methyl-7-isopropyl-5E-undecen-4-olide, isolated from Greek tobacco, has been determined mainly be 1H NMR, 13C NMR and high resolution MS, and its absolute configuration established by degradation to (2S)-5-oxo-2-isopropylhexanal. The carbon skeleton of the new compound indicated that it is derived from a thunbergane precursor and constitutes the first C15 nor-thunberganoid in tobacco.