A compound of Formula: or a pharmaceutically acceptable salt thereof, wherein: R 1 is hydrogen, halogen, or optionally substituted alkyl; each instance of R 3 is independently halogen, -CN, -NO 2, -N 3, optionally substituted alkyl, -OR 3A, -N(R 3B) 2, or optionally substituted acyl; n is 0, 1, 2, 3, 4, or 5; R 4 is hydrogen, optionally substituted alkyl, or a nitrogen protecting group; R 5 is halogen; each of R 2 and R 3A is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or an oxygen protecting group; and each instance of R 3B is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group, or two R 3B are taken together with the intervening atoms to form optionally substituted heterocyclyl; R 6 is hydrogen, halogen, -CN, -NO 2, -N 3, optionally substituted alkyl, -OR 6A,-N(R 6B) 2, or optionally substituted acyl; R 6A is hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or an oxygen protecting group; and each instance of R 6B is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group, or two R 6B are taken together with the intervening atoms to form optionally substituted heterocyclyl. R 1 is hydrogen, halogen, or optionally substituted alkyl; each instance of R 3 is independently halogen, -CN, -NO 2, -N 3, optionally substituted alkyl, -OR 3A, -N(R 3B) 2, or optionally substituted acyl; n is 0, 1, 2, 3, 4, or 5; R 4 is hydrogen, optionally substituted alkyl, or a nitrogen protecting group; R 5 is halogen; each of R 2 and R 3A is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or an oxygen protecting group; and each instance of R 3B is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group, or two R 3B are taken together with the intervening atoms to form optionally substituted heterocyclyl; R 6 is hydrogen, halogen, -CN, -NO 2, -N 3, optionally substituted alkyl, -OR 6A,-N(R 6B) 2, or optionally substituted acyl; R 6A is hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or an oxygen protecting group; and each instance of R 6B is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group, or two R 6B are taken together with the intervening atoms to form optionally substituted heterocyclyl.