Sztmmavy.A total carbon shift analysis of several rcprcstmtdivcs of the lal~danc: ditcqcnc family of natural products is prcscnted. 'J'hc shift assignment is l~ascd on thc prior shift designation of some synthctic trans-decalin derivatives.

Summary. The synthesis of racemic stercoisomcric compounds with the 5,5,9-trimethyldecalin skeleton and an oxygen function at C(1), C(2) or C(3) is described1). h novel general onestep synthesis of 2-decalones by means of acid catalyzed cyclization of acyclic or monocyclic precursors has been developed.

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The four geometrical isomers of 1,3,5-undecatriene, l a 4 have been prepared (stereospecifically and non-stereospecifically), using either (1) the Wittig reaction, (2) thermal sigmatropic hydrogen shifts, (3) partial reduction of triple bonds by zinc, or (4) organocopper reagents. The thermal behaviour of the four 1,3,5-undecatrienes has been investigated and the products formed have been characterized. The spectra of la-d, and of related compounds, have been discussed in order to corroborate their configurational assignment. 1. Introduction. -Some 1,3,5-undecatrienes isolated from the essential oils of both 4. 58; d x d; J = 16; J ' = 7 4. 58; d; J = 7 2.8; d x d; J = 21; J'=12 2. a; d; J = 21 2 . 8 ; d; J = 12 4 . 6 3 ; d x d; J = 15; J ' = 7 4. 63; d; J = 7 5. 58; 12-line system 5. 58; d x t; J = 15; J' = 7 5. 56; d x d; J = 15; J ' = 6 5. 56; d; J = l! 5.33; dxdxt; J = 15; J ' = 6; J I I = 7 5. 33; d x t; J = 1 5 ; J 1 = 7 5.42; d x d; J = 14; J ' = 11 5. 42; d x d; 5.14; J ' = U 5.42; d x d; J = 14; J'= 11 5.96; dxdxt; 5=15; J ' = 6; J I I = 7 5. 96; d x t; J = 15; J ' = 7 5. 07; d with fine splitting; J = 8 / 5.1; d with fine splitting; J = 17 4. 03; d x d; J 10; J' = 2/ 4. 29; d x d; J = 17; J' = 2 4. 03; d; J = 2/ 4. 29; d; J = 2 4.03; d x d ; J = 10; J'= 21 4.29; d x d ; J = 17; J ' = 2Summary. I n the adult male cecropia moth, l-[14C]-propionate is incorporated specifically into juvenile hormone I (1). By chemical degradation it was found that only C(7) and C(11) are labelled, each carbon atom bearing 50% of the radioactivity originally present in J H -I . It is concluded that propionate serves as a precursor of homomevalonate, which in turn is a precursor for J H -I . Application of 2-[W]-propionate and 3-[14C]-propionate leads to extensive randomization of the label. Apparently propionate is metabolized such that C(2) and C(3) can be reused as smaller fragments-probably acetate-while C(l) is either highly diluted or removed from the propionate in a metabolically inactive form.The insect juvenile hormones I and I1 ( J H -I , 1; JH-11, 2 ) are the only known terpenoid compounds where methyl groups biosynthetically derived from C(3') of mevalonate are formally replaced by ethyl groups. They were discovered in adult males of the saturniid moth Hyalophora cecropia [l] [Z] and were also isolated from the related species Hyalophora gloveri [3] and Samia Cynthia [4]. Juvenile hormone is produced by corpora allata, a pair of glands associated with the insect brain. It was *

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