Sulfide alkyl compounds for HBV treatment

A compound of Formula IIIa:

• or a pharmaceutically acceptable salt, solvate, or N-oxide thereof;
• wherein
• each R1 is independently selected from H, halo, and C1-6-alkyl;
• R2 is selected from halo, —OH, —CN, —C1-6-alkyl, —C1-6-alkoxy, halo-(C1-6-alkyl), di-halo-(C1-6-alkyl), and tri-halo-(C1-6-alkyl);
• R3 is halo;
• and
• R4 is selected from —C1-6-alkyl, —C1-6-heteroalkyl, —C3-7-cycloalkyl, —C3-7-heterocycloalkyl,
• (C1-6-alkyl)-(C3-7-cycloalkyl), —(C3-7-cycloalkyl)-(C1-6-alkyl), bridged C7-8-cycloalkyl, —(C1-6-alkyl)-C(O)O—(C1-6-alkyl), and —(C1-6-alkyl)-(C3-7-heterocycloalkyl), wherein R4 may be optionally substituted with one or two groups independently selected from (═O), —OH, —C1-6-alkyl, —C3-7-cycloalkyl, halo-(C1-6-alkyl), di-halo-(C1-6-alkyl), tri-halo-(C1-6-alkyl), C(O)OH, phenyl, and halo;
• or R4 is selected from —(C3-7-cycloalkyl)-C(O)R5 and -(bridged C7-8-cycloalkyl)-C(O)R5, wherein R5 is selected from —N(CH3)2, NS(O)2CH3, and —C3-7-heterocycloalkyl.