US PATENT SUBCLASS 987 / 52
.~.~.~ Six-membered ring shares a N and C atom with a four-membered ring wherein the six-membered ring contains a C or hetero atom in position 5 and no other hetero atom, the four-membered ring contains the single N as hetero atom; e.g., cephalosporins and analogs, etc. (9/6561B)

Current as of: June, 1999
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987 /   HD   ORGANIC COMPOUNDS CONTAINING A Bi, Sb, As, OR P ATOM OR CONTAINING A METAL ATOM OF THE 6TH TO 8TH GROUP OF THE PERIODIC SYSTEM

30  DF  PHOSPHORUS COMPOUNDS (9/02; 9/06) {15}
49  DF  .~ Ring is devoid of a P or a metal atom and contains at least one hereto atom (O, S, N, Se, or Te) and may or may not contain C (9/547; 9/6524) {9}
50  DF  .~.~ At least two rings, each ring containing at least one hetero atom, and wherein the rings are condensed directly to each other or condensed together through a common carbocyclic ring system (9/6561) {3}
52.~.~.~ Six-membered ring shares a N and C atom with a four-membered ring wherein the six-membered ring contains a C or hetero atom in position 5 and no other hetero atom, the four-membered ring contains the single N as hetero atom; e.g., cephalosporins and analogs, etc. (9/6561B)

DEFINITION

Classification: 987/52

Six-membered ring shares a N and C atom with a four-membered ring wherein the six-membered ring contains a C or hetero atom in position 5 and no other hetero atom, the four-membered ring contains the single N as hetero atom; e.g., cephalosporins and analogs, etc. (9/6561B):

(under subclass 50) Subject matter wherein the P compound contains the following ring system. [figure] [caption] R is C, N, O, S, Se, or Te

(1) Note. The degree of saturation between ring atoms is not pertinent for this subclass.