V.1.Three ,four,and six membered compounds containing one , O,N, and S atom .V.2. polycyclic five - and six, membered compounds contaiing one dor s atom -V.3.polycyclic derivatives of pyrrole : polycyclic systems with one nitrogen common to both rings: pyrindine and related compoundsV.4.Quinoline ,isoquinoline, and their bnzo derivatives .V.5.Five membered heterocycles containing two heterocycles containing two hetero atoms and their benzo derivatives