Formal One Carbon Deletion of Indoline Hemiaminals under Tautomeric Control to Access 2-Aminobenzyl Compounds

Unprecedented tert-BuOK-mediated one carbon deletion of indoline hemiaminals has been achieved. This novel protocol provides an efficient synthetic tool for the construction of 2-aminobenzyl compounds with high chemoselectivity. In addition, functionalized 2-aminobenzyl compounds are difficult to make, for which few limited means of access currently exist. The key to success is the use of in situ generated Heyns rearrangement products (α-amino carbonyl compounds) as precursors for formal one carbon deletion.