Organic electroluminescent compound and organic electroluminescent device comprising the same

An organic electroluminescent compound represented by the following formula 1:

• wherein
• when ring A is selected from the following formulas;
• X represents NR11, CR12R13, O, or S;
• R1 each independently represents hydrogen, deuterium, a halogen, or a cyano;
• R11 represents hydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C3-C30 cycloalkyl, a substituted or unsubstituted 3- to 7-membered heterocycloalkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted 3- to 30-membered heteroaryl, a substituted or unsubstituted silyl, or a substituted or unsubstituted amino;
• R12 and R13 each independently represent a halogen, a cyano, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C3-C30 cycloalkyl, a substituted or unsubstituted 3- to 7-membered heterocycloalkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted 3- to 30-membered heteroaryl, a substituted or unsubstituted silyl, or a substituted or unsubstituted amino;
• or are linked to each other to form a ring;
• R21 represents -L1-Ar1, where if R21 is plural, each of R21 may be the same or different;
• L1 each independently represents a single bond, a substituted or unsubstituted C6-C30 arylene aryl, or a substituted or unsubstituted 3- to 30-membered heteroarylene;
• Ar1 each independently represents deuterium, a halogen, a cyano, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C3-C30 cycloalkyl, a substituted or unsubstituted 3- to 7-membered heterocycloalkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted 3- to 30-membered heteroaryl, a substituted or unsubstituted silyl, or a substituted amino;
• and
• a represents an integer of 1 to 4, b represents an integer of 1 to 10, where if and b are an integer of 2 or more, each of R1 and each of R21 may be the same or different;
• * represents a site fused with the 5-membered ring comprising X;
• with the proviso that if X is NR11, ring A is not