151851-02-4Relevant articles and documents
Solvolysis of Tricyclo2,6>hex-3-yl and Bicyclohex-2-yl Sulfonates
Bentley, T. William,Norman, Simon J.,Gerstner, Erwin,Kemmer, Ralf,Christl, Manfred
, p. 1749 - 1758 (2007/10/02)
Solvolyses of cis-tricyclo2,6>hex-3,4-diyl ditosylate (12) and cis-bicyclohex-2,3-diyl ditosylate (27) have been carried out in 80 percent aqueous ethanol in the presence of ethyldiisopropylamine.In the former case, endo,endo-tricyclo2,6>hexane-3,5-diol (13a), its monoether 13b and diether 13c were products whereas in the latter the monoethers 28b, d, e, g and the diethers 28a, c, f of bicyclohexane were formed.In pure ethanol, 12 was converted into pure 13c in good yield.In the presence of the weaker base 2,6-lutidine, the solvolysis of 12 in aqueous ethanol gave different products, i.e. exo,exo-4,6-diethoxybicyclohex-2-ene (14a) and several aldehydes, inter alia cyclopentadiene-1-carboxaldehyde (15).In control experiments, the tricyclic compounds 13b, c were converted into 14a, 15 and further aldehydes as well as into the bicyclohexene derivatives 19a, b.Sulfonates of tricyclo2,6>hexan-3-ol (21a) could not be isolated but its mesylate 21c was characterized by NMR spectroscopy and hydrolysed in aqueous acetone to give tricyclo2,6>hexan-endo-3-ol (22a).It is concluded from these results that the dissociations of the above sulfonates do not lead to unrearranged carbocations.Rather, they proceed with participation of the β-carbon in trans position relative to the leaving group resulting in the immediate generation of rearranged cations. - Kinetic studies show that the tricyclic mesylate 21c solvolyses in 80 percent ethanol/water 1.4*1E5 times as fast as bicyclohex-2-yl tosylate (25), and the tricyclic ditosylate 12 solvolyses 6 * 1E5 as fast as the corresponding bicyclic ditosylate 27.These rate enhancements are similar to those previously observed for less strained cyclopropylcarbinyl substrates.Key Words: Bicyclobutylcarbinyl sulfonates, solvolysis of/ Cyclobutylcarbinyl sulfonates, solvolysis of/ Anchimeric assistance in solvolysis/ Rearrangement of carbocations/ Electron demand in ditosylates