4-hydroxybutyric acid analogs

A compound of the Formula B:

• or a pharmaceutically acceptable salt thereof, wherein:
• A1 is hydrogen, deuterium, —CH2—C(O)OR2′ or —CH(R1′)—C(O)OR2′;
• R1′ is C1-6 alkyl, C2-10 alkoxyalkyl, phenyl, —(C1-3 alkyl)-(C3-6 cycloalkyl), or C3-6 cycloalkyl, wherein R1′ is optionally substituted with C1-3 alkyl, C1-3 alkoxy, phenyl, —O—(CH2CH2O)n—CH3, wherein n is 1, 2, or 3;
• R2′ is hydrogen;
• deuterium;
• —C1-4 alkyl optionally substituted with phenyl;
• —(C3-6 cycloalkyl) optionally substituted with phenyl or methyl;
• —CH2—(C3-6 cycloalkyl) wherein the C3-6 cycloalkyl is optionally substituted with phenyl;
• phenyl;
• or biphenyl;
• X1 is hydrogen, deuterium, —C(O)-indanyl, —C(O)-indenyl, —C(O)-tetrahydronaphthyl, —C(O)—C1-6 alkyl, —C(O)—C1-6 alkenyl, —C(O)—C1-6 alkynyl, —C(O)—C1-3 alkyl optionally substituted with C3-6 cycloalkyl, or —C(O)—C3-6 cycloalkyl optionally substituted with C1-6 alkyl, phenyl or naphthyl;
• and
• each Y is independently selected from hydrogen and deuterium,
• provided that:
• (i) when A1 is hydrogen or deuterium, at least one Y is deuterium;
• and
• (ii) when X1 is hydrogen or deuterium, each Y2 is deuterium, and each Y3 is deuterium, then A1 is not hydrogen or deuterium.