8-66 u B03 - THF .. H202 .. HO-aCH3 111 0 IIIOH H 8-67 By now, these rearrangements should not be so "unexpected" . � n U" "": H�B� H 20 I Cf.�C H C+H�H 3H (YCH3 • alkyl migration with ring expansion gives 3° carbocation in 6-membered ring--carbocation nirvana! H H H + : !lr:0'CH] �Br CH3 You must be asking yourself, "Why didn't the methyl group migrate?" To which you answered by drawmg the carbocation that would have been formed: I;I 2° 3° C+ H O\} � --QC<1''-CH3 CH I "H CH3 3H The new carbocation is indeed 3°, but it is only in a 5-membered ring, not quite as stable as in
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Trigraph, methyl group, Potassium permanganate, methyl group migrate