COMMUNICATIONS TO THE EDITOR
Nov. 5 , 1963
(030 mole) in 370 ml. of boiling tetrahydrofuran for 16 hr. in the presence of an excess of cyclohexene (0.95 mole), 7-isopropylidenenorcarane (111) was isolated (SY,),indicating the intermediate formation of isopropylidenecarbene.
EHz
+
Ii
IV and V
A I
VII, R = C ~ H I ,
The carbene adduct I11 in the n.m.r. spectrum shows the allylic methyl group signals a t 8.25 T , mol. ~ wt. 136 (mass spec.), infrared 3.63 p (>C=Cc=c, 2 6 ; C-3, 1 . 6 ; C-4, 2 % ; (2-3, 1 ; C-6, 24; C - l ' , 1 . 3 ; C-%', 2 2 ; C-:3', l.(j?c. Thus almost all the activity is located on the even numbered carbons and, within experimental error, is equally distributed among these four positions. Our results indicate the danger of drawing conclusions froni tracer work involving unifornily labeled c o n pounds. Presumably the uniformly labeled lysine which was fed to the hemlock plants underwent degradation affording acetate which was then utilized for the synthesis of coniine. V'ork is i n progress to determine whether the eight carbon chain present in coniine is formed by the condensation of one acetylcoenzyme .A with three malonylcoenzy111e .Imolecules.~ ( > ) l i I.eete, ''Hioqenc5is o f S a t u r a l Compounds," P . Bernfeld, E d . , I'erxamon ['res,. Oxf
