Asymmetric synthesis of the northern segment of ephedradine C. A novel dihydrobenzo[b]furan formation

Article abstract of DOI:10.1016/S0040-4039(99)01835-3

An asymmetric synthesis of the dihydrobenzo[b]furan segment of ephedradine C has been achieved utilising a chiral oxazolidinone in an aldol reaction to form a ?2-hydroxy ester, followed by a novel debenzylation and concomitant intramolecular cyclisation with iodotrimethylsilane as key steps. An asymmetric Michael reaction with a homochiral lithium amide was used to form the third and final chiral centre.