1-(2,3,6-Trideoxy-.alpha.-L-glycero-hex-2-enopyranos-4- ulosyl) thymine 5-Methyl-1-(6-methyl-5-oxo-5,6-dihydro-2H-pyran-2-yl)-2,4(1H,3H)-pyrimidinedione AIDS-136695 AIDS136695 NSC638852