prov:value
| - 3 or 4 heteroatoms in the ring which are independently N, S or O; and including N-oxides; X is a bond, or is one of the following groups: wherein Y is O, N-R6 or S; n??? is 0, 1 or 2; R6 is H, lower alkyl, aryl, ???C(O)???R11 or ???C(O)???O???R11; R7 and R8 are the same or different and are independently H, alkyl, aryl, halogen, ???O???R12, or R7 and R8 together can be oxygen to form a ketone; R9,
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