A new method for direct cyclopropylation of arylamines at the ortho-position

Abstract

Carbenoids are reactive intermediates that are useful in organic synthesis because they have both electrophilic and nucleophilic reactivities. Magnesium cyclopropylidenes were generated from 1-chlorocyclopropyl phenyl sulfoxides with i-PrMgCl in THF at -78 temperature by sulfoxide-magnesium exchange reaction. Reaction of the magnesium cyclopropylidenes with N-lithio arylamines was investigated and it was found that the reaction gave ortho-cyclopropylation of arylamines in moderate to good yields. This is the first example of direct cyclopropylation of arylamines on the aromatic ring. The magnesium cyclopropylodenes having at least one substitutent was found to be essential to this C-cyclopropylation.