Anti-Markovnikov reactions Markovnikov's rule

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anti-markovnikov behavior can manifest in rearrangement reactions. in titanium(iv) chloride-catalyzed formal nucleophilic substitution @ enantiopure 1 in scheme below, 2 products formed – 2a , 2b. due 2 chiral centers in target molecule, carbon carrying chlorine , carbon carrying methyl , acetoxyethyl group, 4 different compounds formed: 1r,2r- (drawn 2b) 1r,2s- 1s,2r- (drawn 2a) , 1s,2s- . therefore, both of depicted structures exist in d- , l-form. :




this product distribution can rationalized assuming loss of hydroxy group in 1 gives tertiary carbocation a, rearranges seemingly less stable secondary carbocation b. chlorine can approach center 2 faces leading observed mixture of isomers.


another notable example of anti-markovnikov addition hydroboration.








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