Provided herein is a compound of Formula (1-I): or a pharmaceutically acceptable salt thereof, wherein R.sup.2a, R.sup.2b, R.sup.3, R.sup.4a, R.sup.4b, R.sup.5, R.sup.6a, R.sup.6b, R.sup.11a, R.sup.11b, R.sup.16a, R.sup.16b, R.sup.19, R.sup.18, X, q, r, s, t, u, and n are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (1-I) and methods of using the compounds, e.g, in the treatment of CNS-related disorders.

##STR00001##

Provided herein is a compound of Formula (1-I): or a pharmaceutically acceptable salt thereof, wherein R.sup.2a, R.sup.2b, R.sup.3, R.sup.4a, R.sup.4b, R.sup.5, R.sup.6a, R.sup.6b, R.sup.11a, R.sup.11b, R.sup.16a, R.sup.16b, R.sup.19, R.sup.18, X, q, r, s, t, u, and n are defined herein. Also provided herein are pharmaceutical compositions comprising a compound of Formula (1-I) and methods of using the compounds, e.g, in the treatment of CNS-related disorders.

##STR00001##