| 549 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
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| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {1} |
| * | DD | .~ HETEROCYCLIC CARBON COMPOUNDS CONTAINING A HETERO RING HAVING CHALCOGEN (I.E., OXYGEN, SULFUR, SELENIUM, OR TELLURIUM) OR NITROGEN AS THE ONLY RING HETERO ATOMS (Class 540, subclass 1) {2} |
| 200 | DF | .~.~ Oxygen containing hetero ring (e.g., dioxirane, etc.) {16} |
| 330 | DF | .~.~.~ Spiro {1} |
| 331 |  | .~.~.~.~ The spiro includes a hetero ring {4} |
| 332 | DF | .~.~.~.~.~> The spiro includes a three- or four-membered hetero ring |
| 333 | DF | .~.~.~.~.~> Plural ring oxygens in a spiro hetero ring {3} |
| 343 | DF | .~.~.~.~.~> Both rings which form the spiro are hetero rings {1} |
| 345 | DF | .~.~.~.~.~> Bicyclo ring system having the spiro hetero ring as one of the cyclos (e.g., griseofulvin, etc.) |