2- Octyl brosylate

When bicyclo[2.2.2]octyl brosylate was solvolyzed in acetic acid containing sodium acetate, the products were a mixture of bicyclo[2.2.2]octyl acetate and bicyclo[3.2.1]octyl acetate, each of which was optically active. The formation of bicyclo[2.2.2]octyl acetate was found to proceed with 82 15% retention of configuration, a result which is in... 

The compound 2-octyl brosylate was labeled at the sulfone oxygen with 0 and solvolyzed. The unreacted brosylate recovered at various stages of solvolysis had the 0 considerably, though not completely, scrambled ... 

In a study of the effect of azide ion on the solvolysis of 2-octyl brosylate in aqueous acetone, Raaen et al. (1974) showed that the a-deuterium isotope effects for both the alcohol and azide produced were almost identical (1-097 0-007 and 1-106 0-007 respectively). These results imply that the rate determining step(s) for formation of alcohol and azide are either identical or very similar. A likely explanation is that the two products are formed in parallel... 

Some nucleophilic substitution reactions that seem to involve a borderline mechanism actually do not. Thus, one of the principal indications that a borderline mechanism is taking place has been the finding of partial racemization and partial inversion. However, Weiner and Sneen have demonstrated that this type of stereochemical behavior is quite consistent with a strictly Sn2 process. These workers studied the reaction of optically active 2-octyl brosylate in 75% aqueous dioxane, under which conditions inverted 2-octanol was obtained in 77% optical purity. When... 

Su2 reactions may, however, involve some complexities. An interesting example is the study by Sneen and co-workersof the 5n2 solvolysis of 2-octyl brosylate in the presence of azide ion. In pure methanol or water, solvolysis with inversion occurs. In 75% aqueous dioxan, however, the inverted 2-octanol was obtained in only 77% optical purity. When azide ion was added optically impure 2-octyl azide (3) was obtained together with fully inverted 2-octanol (4). A sequence involving pairallel solvolysis by direct reaction, and reaction through an ion-pair intermediate (5) was put forward to explain these results (equation 19). The formation of the alcohol (6) with reten-... 

When bicyclo[2.2.2]octyl brosylate was solvolyzed in acetic acid containing sodium acetate, the products were a mixture of bicyclo[2.2.2]octyl acetate and... 

Cope and coworkers carried out a product study on acetolysis of the epimeric 3-bicyclo[5.1.0]octyl brosylates (135 and 136) (Scheme 19). However, no kinetics were measured. Formation of the bicyclo[3.3.1]octan-3-yl product from the endo brosylate (135) reveals that some cyclopropyl participation may be involved. 

SCHEME 19 Products of acetolysis of epimeric 3-bicyclo[5.1.0]octyl brosylates ... 

Bicyclooctyl Cations. Solvolyses of endo-2-bicyclo[3.2.1]octyl tosylate (73)55S and 4-cycloheptenylcarbinyl brosylate (4< 7)377 555 give similar product mixtures consisting primarily of endo-2-bicyclo [3.2.1] octanol or its acetate (819)... 

Reactivities of brosylates, mesylates and tosylates are similar (Table 3), and show relatively small variations with solvent and alkyl group (R). Tosylate/mesylate rate ratios vary from 0.5 to 2.0 in S l solvolytic reactions of adamantyl sulphonates48. Slightly higher ratios may be observed for SN2 reactions in dipolar aprotic solvents, e.g. second-order rate constants for nucleophilic substitution in n-octyl sulphonates by thiocyanate anion show tosylate/mesylate rate ratios increasing from 0.7 in methanol to 1.5 in chlorobenzene and in cyclohexane, and to 4.4 in DMSO12. 

The acetolysis of optically active brosylate 157 results in an optically active bicyclo[2,2,2]acetate 160 with 85 15% retention of configuration the second product — the axial 2-bicyclo[3,2,l]octyl acetate 161 (63 35) — turned out to be optically active as well. Not even any traces were found of the more stable equatorial isomer 162. From these data the authors concluded an intervention of the nonclassical ion 158. The degree of retention (85 15%), however, does not preclude the classical ion 159 to play a minor role as well. 

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