Novel nootropic prodrugs of henethylamine

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is selected from hydrogen, methyl and methoxy;
• R2 is selected from hydrogen, trifluoromethyl, methoxy and ethoxy, and
• R3 is selected from hydrogen, halogen, nitro, methyl, ethyl, n-propyl, trifluoromethyl, methoxy, ethoxy, n-propoxy, allyloxy, 2-methylallyloxy, ethylthio, n-propylthio, isopropylthio, cyclopropylmethylthio, tertbutylthio, and 2-fluoroethylthio;
• or
• R2 and R3 together with the carbon atoms that carry R2 and R3, respectively, form a five membered ring selected from
• R4 is selected from hydrogen, methyl and methoxy;
• R5 is selected from hydrogen and methyl;
• X is selected from:
• R6 is selected from C1-5 alkyl and aryl, wherein said aryl is optionally substituted with one or more groups RS;
• R7 is selected from methoxy and hydrogen;
• R8 is C1-5 alkyl;
• R9 is selected from hydrogen, C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, —(C1-6 alkylene)-O—R10, —(C1-6 alkylene)-S—R10, —(C1-6 alkylene)-N(R10)—R10, —(C1-6 alkylene)-CO—R10, —(C1-6 alkylene)-COO—R10, —(C1-6 alkylene)-O—CO—(C1-6 alkyl), —(C1-6 alkylene)-CO—N(R10)—R10, —(C1-6 alkylene)-N(R10)—CO—(C1-6 alkyl), —(C1-6 alkylene)-CO—N(R10)—O—R10, —(C1-6 alkylene)-O—CO—N(R10)—R10, —(C1-6 alkylene)-N(R10)—CO—N(R10)—R10, —(C1-6 alkylene)-N(R10)—C(═N—R10)—N(R10)—R10, —(C1-6 alkylene)-SO3—R10, —(C0-6 alkylene)-carbocyclyl, and —(C1-6 alkylene)-heterocyclyl, wherein the carbocyclyl group in said —(C0-6 alkylene)-carbocyclyl and the heterocyclyl group in said —(C0-6 alkylene)-heterocyclyl are each optionally substituted with one or more groups RS, wherein said alkyl, said alkenyl, said alkynyl, and any alkylene group comprised in any of the aforementioned R9 groups are each optionally substituted with one or more —OH, and further wherein each R10 is independently selected from hydrogen and C1-6 alkyl;
• R11 is a C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, carbocyclyl or heterocyclyl, wherein said alkyl, said alkenyl, said alkynyl, said carbocyclyl and said heterocyclyl are each optionally substituted with one or more RS;
• and
• each RS is independently selected from C1-5 alkyl, C2-5 alkenyl, C2-5 alkynyl, —(C0-3 alkylene)-OH, —(C0-3 alkylene)-O(C1-5 alkyl), —(C0-3 alkylene)-O(C1-5 alkylene)-OH, —(C0-3 alkylene)-O(C1-5 alkylene)-O(C1-5 alkyl), —(C0-3 alkylene)-SH, —(C0-3 alkylene)-S(C1-5 alkyl), —(C0-3 alkylene)-S(C1-5 alkylene)-SH, —(C0-3 alkylene)-S(C1-5 alkylene)-S(C1-5 alkyl), —(C0-3 alkylene)-NH2, —(C0-3 alkylene)-NH(C1-5 alkyl), —(C0-3 alkylene)-N(C1-5 alkyl)(C1-5 alkyl), —(C0-3 alkylene)-NH—OH, —(C0-3 alkylene)-N(C1-5 alkyl)-OH, —(C0-3 alkylene)-NH—O(C1-5 alkyl), —(C0-3 alkylene)-N(C1-5 alkyl)-O(C1-5 alkyl), —(C0-3 alkylene)-halogen, —(C0-3 alkylene)-(C1-5 haloalkyl), —(C0-3 alkylene)-O—(C1-5 haloalkyl), —(C0-3 alkylene)-CN, —(C0-3 alkylene)-NO2, —(C0-3 alkylene)-CHO, —(C0-3 alkylene)-CO—(C1-5 alkyl), —(C0-3 alkylene)-COOH, —(C0-3 alkylene)-CO—O—(C1-5 alkyl), —(C0-3 alkylene)-O—CO—(C1-5 alkyl), —(C0-3 alkylene)-CO—NH2, —(C0-3 alkylene)-CO—NH(C1-5 alkyl), —(C0-3 alkylene)-CO—N(C1-5 alkyl)(C1-5 alkyl), —(C0-3 alkylene)-NH—CO—(C1-5 alkyl), —(C0-3 alkylene)-N(C1-5 alkyl)-CO—(C1-5 alkyl), —(C0-3 alkylene)-NH—CO—O—(C1-5 alkyl), —(C0-3 alkylene)-N(C1-5 alkyl)-CO—O—(C1-5 alkyl), —(C0-3 alkylene)-O—CO—NH—(C1-5 alkyl), —(C0-3 alkylene)-O—CO—N(C1-5 alkyl)-(C1-5 alkyl), —(C0-3 alkylene)-SO2—NH2, —(C0-3 alkylene)-SO2—NH(C1-5 alkyl), —(C0-3 alkylene)-SO2—N(C1-5 alkyl)(C1-5 alkyl), —(C0-3 alkylene)-NH—SO2—(C1-5 alkyl), —(C0-3 alkylene)-N(C1-5 alkyl)-SO2—(C1-5 alkyl), —(C0-3 alkylene)-SO2—(C1-5 alkyl), —(C0-3 alkylene)-SO—(C1-5 alkyl), —(C0-3 alkylene)-carbocyclyl, and —(C0-3 alkylene)-heterocyclyl, wherein the carbocyclyl moiety in said —(C0-3 alkylene)-carbocyclyl and the heterocyclyl moiety in said —(C0-3 alkylene)-heterocyclyl are each optionally substituted with one or more groups independently selected from C1-4alkyl, halogen, —CN, —NO2, —OH, —O—(C1-4alkyl), —SH, —S—(C1-4alkyl), —NH2, —NH(C1-4alkyl), —N(C1-4alkyl)(C1-4 alkyl), —COOH, —COO(C1-4 alkyl), —CONH2, —CONH(C1-4 alkyl), —CON(C1-4 alkyl)(C1-4 alkyl), —NHCO(C1-4 alkyl) and —N(C1-4alkyl)-CO(C1-4alkyl);
• wherein if X is
• then R1 is hydrogen, R2 and R3 together with the carbon atoms that carry R2 and R3, respectively, form a five membered ring being
• R4 is hydrogen, and R5 is methyl;
• wherein if X is
• and if R11 is a C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, or carbocyclyl, wherein said alkyl, said alkenyl, said alkynyl and said carbocyclyl are each optionally substituted with one or more RS, then R1 is hydrogen, R2 is methoxy, R3 is methoxy, R4 is methoxy, and R5 is hydrogen.