Halo-substituted piperidines as orexin receptor modulators

A compound of formula (I),

• or a pharmaceutically acceptable salt thereof, wherein:
• X is halogen;
• X′ is H or halogen;
• Z is NR2 or O;
• A is aryl, aroyl, heteroaryl, or heteroaroyl, wherein A is optionally substituted with one or more substituents independently selected from the group consisting of alkyl, cycloalkyl, halo, —OH, alkoxy, —CHF2, —CF3, —CN, —NRaRb, —N(Ra)C(O) alkyl, —N(Ra)CO2alkyl, —N(Ra)SO2alkyl, —C(O)alkyl, —CO2H, —CO2alkyl, —CONRaRb, —SO2alkyl, and SO2NRaRb;
• wherein Ra and Rb are independently for each occurrence H or alkyl;
• B is aryl or heteroaryl, wherein B is optionally substituted with one or more substituents independently selected from the group consisting of alkyl, cycloalkyl, halo, —OH, alkoxy, —CH2CF3 , —CHF2, —CF3, —CN, —NRcRd, —N(W)C(O) alkyl, —N(Rc)CO2alkyl, —N(Rc)SO2alkyl, —C(O)alkyl, —CO2H, —CO2alkyl, —CONRcRd, —SO2alkyl, and —SO2NRcRd;
• wherein Rc and Rd are independently for each occurrence H or alkyl;
• E is aryl or heteroaryl, wherein E is optionally substituted with one or more substituents independently selected from the group consisting of alkyl, cycloalkyl, halo, —OH, alkoxy, —CHF2, —CF3, —CN, —NReRf, —N(Re)C(O) alkyl, —N(Re)CO2alkyl, —N(Re)SO2alkyl, —C(O)alkyl, —CO2H, —CO2alkyl, —CONReRf, —SO2alkyl, and —SO2NReRf;
• wherein Re and Rf are independently for each occurrence H or alkyl;
• n=1, 2, or 3;
• R1 is alkyl;
• and
• R2 is H or alkyl.