Synthesis of tyrosine-derived tetrahydroisoquinolines by Lewis acid catalyzed cyclization of N-(phenylsulfonyl)alkyloxazolidinones

Article abstract of DOI:10.1002/ejoc.200700443

N-Boc-protected tyrosine esters 5a,b were converted into tetrahydroisoquinolines 13 and 14 in four steps by reduction and ring closure to oxazolidinones 9 and 10, addition of benzenesulfinic acid and aldehydes to sulfones 11 and 12 and subsequent Lewis ac