The present invention relates to inhibitors of zinc-dependent histone deacetylases (HDACs) useful in the treatment of diseases or disorders associated with HDAC6, having a Formulae I or Formula II: ##STR00001## where R, L, X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, Y.sup.1, Y.sup.2, Y.sup.3, and Y.sup.4 are described herein.

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor. ##STR00001##

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor. ##STR00001##

Provided herein are compounds of formulae (I)-(IX), or pharmaceutically acceptable salts or deuterated forms thereof as defined herein. Also provided herein are pharmaceutical compositions comprising a compound of formula (I)-(IX) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of formula (I)-(IX) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

Provided herein are compounds of formulae (I)-(IX), or pharmaceutically acceptable salts or deuterated forms thereof as defined herein. Also provided herein are pharmaceutical compositions comprising a compound of formula (I)-(IX) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of formula (I)-(IX) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

Provided herein are compounds of Formula (I), or pharmaceutically acceptable salts or deuterated forms thereof, wherein R.sup.0, L and R.sup.1 are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, and methods of using a compound of Formula (I) or pharmaceutically acceptable salt or deuterated form thereof, e.g., in the treatment of a disease that is treatable by administration of a DPP1 inhibitor.

##STR00001##

A compound represented by general formula (1) or a pharmacologically acceptable salt thereof for inhibiting 15-PDGH.