Two of the cyclos share at least three ring members (i.e., bridged)

Subclass of:

546 - Organic compounds -- part of the class 532-570 series

546000000 - ORGANIC COMPOUNDS (CLASS 532, SUBCLASS 1)

546000000 - 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)

546001000 - Hetero ring is six-membered consisting of one nitrogen and five carbons

546026000 - Polycyclo ring system having the six-membered hetero ring as one of the cyclos

546042000 - Pentacyclo ring system having the six-membered hetero ring as one of the cyclos

Patent class list (only not empty are listed)

Deeper subclasses:

Class / Patent application number	Description	Number of patent applications / Date published
546044000	One of the five cyclos is five-membered and includes ring chalcogen (e.g., codeine, morphine, etc.)	116