Approach to novel isotetronic acid derivatives: DBu-et3n-mediated aldol/lactonization/O-protection sequence of 2-oxocarboxylic esters

Abstract

An efficient synthesis of novel O-protected isotetronic acids is described. The method relies DBU (1,8-diazabicyclo[5.4.0]-undec-7-ene) and triethylamine triggered homo-aldol reactions 2-oxocarboxylic esters, followed by successful ring closure via lactonization and O-protection with various electrophiles. The unprotected isotetronic acids were also achieved with moderate to high yields if the free-OH group were pre-capped by the silylation agent TMSCl. All the three reaction steps were conducted in a sequential manner, without isolation of any intermediates.