Starting from 5-chloro-2-pentanone ( 1) the naturally occurring 10-membered lactone phoracantholide J ( 8a) has been synthesized as its racemate in a sequence of six steps ( Scheme 2). Salient features of the syntheis include an internal selenium assisted acetal formation ( 4→5) and a stereoselective Claisen rearrangement ( 6→7→8). This general synthetic strategy offers an alternative approach towards the construction of macrocyclic lactones.