Nucleophilic Reactions at Tertiary Carbon. Part 3. σ‐ and π‐routes to the 9‐decalyl cation

Abstract

(28. I X . 73) Summury. The generation of the 9-decalyl cation by solvolysis o f cis-and trans-!-decalyl chloride (1) has been reinvestigated. The results of product, ratc and isomerization studies implicate stereoisomeric ion pairs as intermediates, as in the case of the solvolysis of other stereoisomeric tertiary chlorides (Parts 1 and 2).On the othcr hand, both synimetrically and unsymmetrically solvated 9-decalyl cations are indicated in the cyclization of 4-(cyclohexcn-l -yl)butyl tosylate. No evidcnce was obtained that conformational isomers of the 9-decalyl cation play a role as product dctcrmining intermediates.In an earlier communication [l] we described the generation of the 9-decalyl cation 3 by solvolysis of cis-and fans-9-decalyl chloride, cis-and trans-la respectively, and by cyclization of 4-(cyclohexen-l-yl)butyl tosylatc 2c in 80% ethanol. Since different mixturcs of products, namely olefins, alcohols and ethers, were obtained by these so-called c-and n-routes [Z] it was concluded that the intermediatcs were not identical.Ion pairs which differ with respect t o the location of the counter ion, i.e. tlie chloride ion in 3a, were first considered. However, an explanation based solely on an encumbered carbenium ion was rejected in view of the relatively large difference of 1.4 kcal/molc between the free energies of the transition states for cis-and t r a m l a .

Biogenetic-Type Rearrangements of Terpenes

“…Yield (Optical Purity) 42 -44 OH eJ (11- Three different types of structures have been advanced for the carbonium ionintermediates in these, and other (45)(46)(47), solvolytic reactions in order to account for stereoselectivity. One is the symmetrically bridged non-classical ion (A), which was favored at the time by ÜOERING and PICKES (42)(43)(44).…”

Regioselective Hydrochlorination: An Experiment for the Undergraduate Laboratory

“…The stereochemistry of the hydrochlorination can be studied using octalin. Formation of the trans product is easily followed by IR spectroscopy as the diagnostic band at 543 cm ᎑1 increases (6).…”