Treatment of the lactal 2 with a nucleophile, such as a cyclic allylsilane 6, in the presence of a Lewis acid, such as {HEAD ~ BF3 OEt2}, affords {TAIL ~ the final product} 3 
Treatment of the lactal 2 with a nucleophile , such as a cyclic allylsilane 6 , in the presence of a Lewis acid , such as { HEAD ~ BF3 OEt2 } , affords { TAIL ~ the final product } 3
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH