Antibacterial compounds, pharmaceutical compositions, and methods of treating bacterial infections

A compound having a structure of Formula (I):

• wherein R1, R2, R3, and R4 are each independently selected from the group consisting of an electron pair, H, OH, protected hydroxyl, alkyl, alkenyl, alkynyl, acyl, aryl, heteroaryl, cycloalkyl, phenyl, carbonate ester, a carboxylate, a carboxyl, an ester, a hydroperoxy, a peroxy, an ether, a hemiacetal, a hemiketal, an acetal, a ketal, an orthoester, a methylenedioxy, an orthocarbonate ester, carboxamide, an amine, an imine, an amide, an azide, an azo, a cyanate, a nitrate, a nitrile, an isonitrile, a nitrosooxy, a nitro, a pyridyl, a thiol, a sulfide, sulfinyl, a sulfonyl, a thiocyanate, a carbonothioyl, a phosphate, and heterocycle;
• optionally wherein the alkyl, alkenyl, alkynyl or acyl is substituted with one or more substituents independently selected from the group consisting of halogen, —OH, alkyl, —O-alkyl, NRARB, —S-alkyl, —SO-alkyl, —SO2-alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, and heterocycle;
• wherein RA and RB are each independently selected from hydrogen and C1-4 alkyl;
• wherein the aryl or heteroaryl, whether alone or as part of a substituent group, is optionally substituted with one or more substituents independently selected from the group consisting of halogen, —OH, alkyl, —O-alkyl, —COOH, —C(O)—C1-4 alkyl, —C(O)O—C1-4 alkyl, NRCRD, —S-alkyl, —SO-alkyl and —SO2-alkyl;
• wherein RC and RD are each independently selected from hydrogen and C1-4 alkyl;
• wherein X is C or S;
• or a pharmaceutically acceptable salt or ester thereof.