Retro-Mannich reactions of 3-alkyl-3,4-dihydro-2H-1,3-benz[e]oxazines and the synthesis of axially chiral resorcinarenes

Intermediates involved in the conversion of 3-alkyl-3,4-dihydro-2H-1,3-benz[e]oxazines into 2-N,N-dialkylaminomethylphenol derivatives, using morpholine and other high boiling secondary amines, have been identified and characterised. Additional experiments have established the involvement of o-quinone methide intermediates in the retro-Mannich reactions. Axially chiral resorcinarenes have been prepared by utilising the exchange reactions.