Derives du -butyl-3 cyclohexene. III.- Les quatre chlorhydrines-trans du -butyl-3 cyclohexene

Regio- and stereoselectivity of the formation of halohydrins from 3-methyl- and 3-tert-butylcyclohexene and from the corresponding epoxides

“…12 The reference trans chlorohydrins 4f-7f had already been described. 13 The product distributions found for the various addition reactions, as reported in Table I, confirm the largely different steric courses between the IV-bromoamide-promoted reactions on one hand and the additions of HOBr or AcOBr on the other (Table I).…”

“…In contrast, no such difference was apparent in the steric course of the chlorohydrin formation by the NCS reaction, which was very similar to that reported for the addition of chlorine in the presence of aqueous sodium carbonate. 13 For comparison purposes, the reaction of epoxides 2a and 3a with hydrogen bromide and chloride was also examined.…”

Epoxycarbinyl solvolyses. Lack of significant participation by epoxide oxygen in the hydrolysis of acyclic secondary epoxycarbinyl substrates

“…(3) anti -Epoxycarbinyl brosylate 3b yielded a significantly greater amount (17%) of cycloheptenecarboxaldehyde (7) than syn isomer 2b. A possible intermediate in the formation of 7 is the trans-fused bicyclic hemiketal 20 (Scheme II), which corresponds in structure to the trans-fused cyclobutanol 13 from anti -cyclopropylcarbinyl p-nitrobenzoate 5b.…”

Oxydation des alcènes par l'ion thallique. I. Stéréochimie et mécanisme de l'oxydation des cyclohexènes

“…L'ouverture de l'ion pontC cis 13 donne exclusivement un seul organothalleux 15 alors que son isomkre trans 14 en donne deux, 16 et 17. Ceci est analogue a l'ouverture d'ions pontks de ce type observts dans l'addition Clectrophile sur le tert-butyl-3 cyclohexkne (6) et (7).…”

“…De plus, l'identification des quatre diols isombres conformationnels est possible par comparaison avec les produits purs (6). La nature des diols obtenus permet de prCciser la stCrCochimie de la rCaction, et ceci en comparaison avec les Ctudes d'addition Clectrophile effectukes sur ce systbme (7).…”