The Lithium-Ethylenediamine System. II. Isomerization of Olefins and Dehydrogenation of Cyclic Dienes^1,2

Abstract

The solution formed from the reaction of lithium with ethylenediamine, which probably contains H,NCHtCHZNHLi, is capable of rapidly and quantitatively isomerizing a terminal olefin to an internal olefin. A cyclic diene (such as 4vinyl-cyclohexene) is converted to the corresponding aromatic hydrocarbon, with evolution of hydrogen gas; this reaction takea place slowly even at room temperature. The correaponding sodium compound, HsNCH2CH2NHNa, isomerizes olefinic double bonds a t a very slow rate; however it will rapidly aromatize a cyclic diene in which the double bonds are already conjugated and in the ring.

Stereoselective Conversion of Campholene‐ to Necrodane‐Type Monoterpenes. Novel Access to (−)‐(R,R)‐ and (R,S)‐α‐Necrodol and the Enantiomeric γ‐Necrodols

“…The fact that LEDA initiates C=C bond isomerisation by allylic deprotonation [7] indicates that the small amount of (-)-5 (14%) formed from (-)-3 (Entry I ) may have its origin in the low steric accessibility of H-C(3) due to the cis-oriented CH,OH-C(1). In contrast, for (-)-4, in which H-C(3) is as readily accessible as H-C(5), both isomerisation products (-)-2 and (-)-5 are formed in comparable amounts.…”

“…Alcohol(-)-3(1.8 g, 11.7 mmol) was added to a freshly prepared soh. of Li (0.485 g, 69 mmol) in ethylenediamine (10.8 ml) [7] heated at 70" until the disappearance of (-)-3 (i.e. 8-10 min (GC control); Condition a), then poured onto ice, extracted with Et,O, washed with sat.…”

Die Überführung von (+)‐Δ3 Caren in (+)‐Δ4‐Caren

“…Neben der direkten Umwandlung von 1 in 2 fanden wir noch einen weiteren Weg zum (+)-d4-Caren (2), der uber sauerstoffhaltige Derivate des (+)-d3-Carens (1) fuhrte. Das wichtigste Zwischenprodukt stellte dabei das (+)-trans-4-Acetoxycaran (6) dar, das Acetylierungsprodukt des (+)-trans-4-Hydroxycarans (5) [15], das durch lheses Reagenz wurcle zur Isomerisierung von Homoallylverbindungcn in 1,3-Dienen empfoh-Icn [12]. Limonen und Phellandren isomerisieren sich dabei unter gleichzeitiger Dehydrierung.…”

Transpositions de doubles liaisons dep‐menthènes et dep‐menthadiènes catalysées par des bases

“…Au cours des annCes rCcentes, nombre d'auteurs ont Ctudi6 l'action de bases sur des terpbnes, des dihydro-terpbnes, en utilisant notamment la hi-lithio-6thylbnediamine [29] [46-501, le t-butylate de potassium [13] [40] [50] [51], le benzyl-sodium [Z] [7] [52] [53]. L'isomCrisation d'u-pinbne en b-pinbne, fort intkressante du point de vue industriel, a donne!…”