Arternisia and Tanncetzrm (fam. Compositae) are widely-distributed genera each comprising several hundred species. Several leaf oils of Artemisia species have been used medicinally and industrially, and rlunierous phytochemical investigations have been made (Fa h m y et al. 1 9 6 0 ) but few (e g., K h is a m u t d i n o v and and G o r y a e v 1959; G o r y a e v et al. 1962, 1964; M a n j a r r e z and M e d i n a 1964; I s h i b a s h i et al. 1965; T s u b a k i et al. 1966; G o r y a e v et al. 1 9 6 8 ) are acceptable by modern standards. T. vulgare L. is the only member of the other genus that has been similarly quantitatively investigated (v o n R u d l o f f and U n d e r h i l l 1965; B a n t h o r p e and W i r z -J u s t i c e 1 9 6 9 ) . In order to find sources of camphor and thujone suitable for biosynthetic studies we have screened the leaf oils of various Artenzisia and Tanaceturn species grown under the same conditions in England. A secondary objective was to determine any monoterpene pattern characteristic of these two genera. Experimental a) Plnnt Material. Many mature specimens were obtained from the Royal Botanic Gardens, Kew, and the Chelsea Physic Garden, London. Young plants of other species were purchased from Messrs. Hillier, Winchester; and A. cnlifornica was obtained from Professor C. M ii l l e r , Santa Barbara, California, and naturalised for 18 months. Seeds of the other species were obtained from Botanical Gardens a t Barcelona, Rome, Naples, Pisa, Palermo and Istanbul and were cultivated outdoors in Central London.h) Analysis of Oils. Freshly gathered foliage (late September; terminal 20 cm of mature shoots; SO to 200 gm) was pulverised in liquid nitrogen and extracted with petroleum spirit, b. p. 40' (ca. 20 ml). T h e solid residue was steam distilled with the receiver a t -78'; the distillate was salted-out with ammonium sulphate and extracted with the organic fraction previously collected. This procedure is much more efficient than the traditional steam-distillation process (cf. S c h r a t z and W a h li g 1965). Typically, yields of oil were 0.2 to 1.5% of the wet weight of the foliage.The extract was analysed by gas-liquid chromatography (glc) and then concentrated (to about 4 ml.) to enable the major components to be separated by preparative-scale glc for spectral identification. Helical copper columns (600 cm X 0.6 mm o. d.) were used in either a Pye Mark 104 or a Griffin and George Mark 111 Flame-Ionisation Chromatograph with four stationary phases; (i) Carbowax 20M (10% WIW), (ii) (3-0-oxydipropionitrile (10% WIW), (iii) APEC (10% WIW) and (iv) dionyl phthalate (15% W/W) all coated on G-Cel (60-80 mesh; acid-alkali washed).Operating temperatures were 75' and 150' in turn; the gas flow (nitrogen) was 50 ml min. -'; and the injector ports and detectors were held 10' lower than the column. N o dehydration or isomerisatiocl of standards occt~rred under these conditions. Banthorpe et al., Heft 2 Compounds present in greater than 5% W/W of the oil were isolated and char...

Camphor biosynthesised from [2-14C] mevalonic acid by Artemisia californica or Salvia leucophylla L., and (r) -camphor similarly formed by Chrysanthemum balsamita L., contained 73-83% of the incorporated tracer at C-6 atom. The balance was fairly evenly distributed amongst the other carbon atoms. lsopentenyl pyrophosphate was thus the predominant radioactive precursor and, as was found for thujane derivatives produced by related species, that part of the skeleton derived from 3.3-dimethylallyl pyrophosphate was not equivalently labelled.The similarity of the labelling pattern for both optical isomers is consistent with each being formally derived from the cation formed from the corresponding enantiomer of a-terpineol by addition of the positive centre to the double bond. The formation of both optical isomers of camphor from a particular enantiomer of a-terpineol by cyclisation to C-2 and C-6, respectively, was ruled out.

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Acetal formation is preferred to reduction when pyridinium salts of 3-keto-steroid sulphates are treated with sodium borohydride in anhydrous methanol, whereas alkali-metal salts are reduced in the normal way. This difference is explained by the acidity of the pyridinium ion, which is sufficient to promote acetalisation of unhindered ketones. Significant variations occur in the ratio of the epimeric alcohols formed in the presence of added cations.