| 540 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
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| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {1} |
| 1 | DF | .~ HETEROCYCLIC CARBON COMPOUNDS CONTAINING A HETERO RING HAVING CHALCOGEN (I.E., OXYGEN, SULFUR, SELENIUM OR TELLURIUM) OR NITROGEN AS THE ONLY RING HETERO ATOMS {6} |
| 2 | DF | .~.~ Cyclopentanohydrophenanthrene ring system containing {10} |
| 6 | DF | .~.~.~ Spiro {3} |
| 7 |  | .~.~.~.~ Plural spiro atoms {4} |
| 8 | DF | .~.~.~.~.~> The cyclopentanohydrophenanthrene ring system is part of a polycyclo ring system having at least five cyclos {1} |
| 10 | DF | .~.~.~.~.~> The cyclopentanohydrophenanthrene ring system shares spiro atoms with two hetero rings, each of which contains two oxygens (e.g., 3,17-bis-ketals, etc.) |
| 11 | DF | .~.~.~.~.~> The cyclopentanohydrophenanthrene ring system shares a spiro atom with a lactone ring (i.e., -C(=X)-O- is part of the ring, wherein X is chalcogen) |
| 12 | DF | .~.~.~.~.~> Plural oxygens in both rings which share a spiro atom (e.g., 17,20;20,21 bismethylenedioxy-pregnanes, etc.) {2} |