Solvolysis of 4-tosyloxytwistanes: the relationship between 4-twistyl and 10-protoadamantyl cations

Bromination and Accompanying Rearrangement of the Polycyclic Oxetane 2,4-Oxytwistane

“…Thus, the unsubstituted twist-2-ylium ion ( 30 ) cannot decay via facile E1 thereby possibly increasing its lifetime. In contrast, a trace amount of twist-4-ene ( 24 ) was formed during acetolysis of tosylate 21 (Schemes a and b) . It does not violate Bredt’s rule.…”

“…Oxetane 2 is thus able to reveal which of the two possible C–O heterolyses is preferred by virtue of which product (set) is formed. Separate acetolysis studies using twist-2-yl and twist-4-yl tosylates have been reported. , Acetolysis of twist-4-yl tosylate ( 21 ) produced an equilibrium mixture of twist-4-yl acetate ( 22 ) and protoadamant-10-yl acetate ( 23 ) and a trace amount of twist-4-ene ( 24 ) (Scheme a) . The agency of a pentacoordinate − carbocation (i.e., carbonium ion) was proposed in favor of a rapidly equilibrating mixture of classical tricoordinate , carbocations in order to explain the skeletal rearrangement .…”

“…Separate acetolysis studies using twist-2-yl and twist-4-yl tosylates have been reported. , Acetolysis of twist-4-yl tosylate ( 21 ) produced an equilibrium mixture of twist-4-yl acetate ( 22 ) and protoadamant-10-yl acetate ( 23 ) and a trace amount of twist-4-ene ( 24 ) (Scheme a) . The agency of a pentacoordinate − carbocation (i.e., carbonium ion) was proposed in favor of a rapidly equilibrating mixture of classical tricoordinate , carbocations in order to explain the skeletal rearrangement . The C-1–O-2 bond in oxetane 2 does not break because the product, which was concluded to be 13 , possesses neither a twistyl (e.g., 6 ) nor a protoadamantyl (e.g., 18 ) skeleton.…”

“…Since the O atom of an oxetane is linked to two C atoms, the nucleofugal group is not a traditional leaving group, per se, until the first C–O bond is broken. The identity of that bond introduces a dichotomous situation in which the chemistry of oxetane 2 might parallel that of one of the corresponding p -toluenesulfonic (Ts) esters, , which undergo skeletal rearrangement during S N 1 solvolysis. Indeed, tricyclic C 10 H 16 isomers 1 , isotwistane ( 3 ; (1 r ,3 S ,6 R ,7 r )-tricyclo[4.3.1.0 3,7 ]decane), and protoadamantane ( 4 ; rac -(1 R ,3 S ,6 R ,8 R )-tricyclo[4.3.1.0 3,8 ]decane) are intertwined in a complex web of mechanisms with adamantane ( 5 ; tricyclo[3.3.1.1 3,7 ]decane) at its center .…”

The Novel Adamantane Isomer 2,5‐Trimethylenenorbornane (Tricycio‐[5.3.0.3,9]decane, 4‐Homotwistbrendane)

“…Neither base-nor acid-catalyzed solvolysis of protoadamantan-loendo-yl p-toluenesulfonate (S), the saturated analogue of 3, yielded rearranged 2,5-trimethylenenorbornanols, but only endo-(9) [6] and exo-protoadamantan-10-ol(l0) [6] as the primary products. [7]), MeOH; e) Pyridinium dichromate, pyridinium trifluoracetate, CHzC12 [8];…”