New natural products isolated from one-seeded Juniperus of the southwestern United States:: Isolation and occurrence of 2-ethenyl-3-methyl phenol and its derivatives

Re-examination of the leaf essential oils of the one-seeded, serrate leaf junipers of the Southwestern United States and northern Mexico, by GC GC/MS and NMR, has yielded 2-ethenyl-3-methyl phenol (coahuilensol), 2-ethenyl-3-methyl anisole (coahuilensol, methyl ether), and 2-(1'-acetoxyethyl)-3-methyl anisole (pinchotene acetate) as new natural products. A survey of Juniperus oils revealed that these compounds were found in: three serrate leaf junipers (J. angosturana, two varieties of J. coahuilensis, and J. pinchotii). Coahuilensol was also found in the oils of two smooth leaf junipers of the western hemisphere (J. virginiana var. virginiana and J. v. var. silicicola); three multiple seeded, smooth leaf junipers of the eastern hemisphere (J. semiglobosa, J. semiglobosa J. semiglobosa var. talassica, and J. thurifera). The phenolic compounds were not found in section Juniperus, section Caryocedrus or in the one seeded, smooth leaf junipers of the eastern hemisphere. Coahuilensol has been previously reported as 2-(2-propenyl)-phenol (tentative). The leaf oils of J. angosturana J. coahuilensis, J. coahuilensis var. coahuilensis, J. monosperma and J. pinchotii were re-examined based on fresh oil collections and the compositions are reported. NMR data and mass spectra of the three 3-methyl phenols are presented to aid in future identification.