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Solvolysis of Tricyclo[3.1.0.0 2,6 ]hex‐3‐yl and Bicyclo[2.1.1]hex‐2‐yl Sulfonates
Author(s) -
Bentley T. William,
Norman Simon J.,
Gerstner Erwin,
Kemmer Ralf,
Christl Manfred
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260735
Subject(s) - chemistry , solvolysis , bicyclic molecule , aqueous solution , medicinal chemistry , carbocation , hydrolysis , hexene , hexane , yield (engineering) , stereochemistry , organic chemistry , catalysis , ethylene , materials science , metallurgy
Solvolyses of cis ‐tricyclo[3.1.0.0 2,6 ]hex‐3,4‐diyl ditosylate ( 12 ) and cis ‐bicyclo[2.1.1]hex‐2,3‐diyl ditosylate ( 27 ) have been carried out in 80% aqueous ethanol in the presence of ethyl‐diisopropylamine. In the former case, endo,endo ‐tricyclo[2.2.0.0 2,6 ]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 bicyclo[3.1.0]hexane 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‐diethoxybicyclo[3.1.0]hex‐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 bicyclo[2.1.1]hexene derivatives 19a, b . Sulfonates of tricyclo[3.1.0.0 2,6 ]hexan‐3‐ol ( 21a ) could not be isolated but its mesylate 21c was characterized by NMR spectroscopy and hydrolysed in aqueous acetone to give tricyclo[2.2.0.0 2,6 ]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% ethanol/water 1.4 · 10 5 times as fast as bicyclo[2.1.1]hex‐2‐yl tosylate ( 25 ), and the tricyclic ditosylate 12 solvolyses 6 · 10 5 as fast as the corresponding bicyclic ditosylate 27 . These rate enhancements are similar to those previously observed for less strained cyclopropylcarbinyl substrates.