Total synthesis and absolute stereochemistry of (+)-batzellaside B and its C8-epimer, a new class of piperidine alkaloids from the sponge Batzella sp.

The first total synthesis of (+)-batzellaside B and its C8-epimer was completed from a known l-arabinose-derived tribenzyl ether in 22 steps with overall yields of 3.9% and 5.4%, respectively. The absolute configuration of (+)-batzellaside B was unambiguously determined to be 1S,3S,4S,5R,8S by the Mosher analysis of a synthetic intermediate prepared through a separate route.