| abstract |
Described are compounds of formula (1) (One) here R 1 And R 2 is the same or different, linear or branched alkyl each consisting of 1 to 9 carbons, or alkenyl or alkynyl composed of 2 to 11 carbons; L 1 and L 2 are the same or different and each form a linear alkyl composed of 5 to 18 carbons, or a heterocycle having N; X 1 is a bond, or -CO-O- whereby L 2 -CO-OR 2 is formed; X 2 is S or O; L 3 is a bond or lower alkyl, or forms a heterocycle with N; R 3 is lower alkyl; And R 4 and R 5 are the same or different, each lower alkyl; Or a pharmaceutically acceptable salt thereof. |