New development of Meyers' methodology: stereoselective preparation of an axially chiral 5,7-fused bicyclic lactam related to circumdatins/benzomalvins and asperlicins

The stereoselective preparation of a new Meyers' bicyclic lactam-bridged biaryl 1, highly structurally related to circumdatins, benzomalvins and asperlicins, is reported. Using the popular Meyers' diastereoselective lactamization, under dehydrating conditions (CH2Cl2/reflux/MgSO4), trans-(aS,R,S)-1 was obtained in a rather modest yield of 25% and an excellent diastereoselectivity >95%. An alternative procedure making use of the activating agents of carboxylic acid (Mukaiyama reagent and FEP) allowed the lactamization process to take place under milder conditions (CH2Cl2/20 °C) affording trans-(aS,R,S)-1 in fairly good yields (50%-85%) and in up to 65% de.