Compounds and compositions for intracellular delivery of therapeutic agents

A compound of Formula (IA):

• or a salt or isomer thereof, wherein
• l is selected from 1, 2, 3, 4, and 5;
• m is selected from 5, 6, 7, 8, and 9;
• M1 is a bond or M′;
• R4 is unsubstituted C1-3 alkyl, or —(CH2)nQ, in which Q is OH, —NHC(S)N(R)2, —NHC(O)N(R)2, —N(R)C(O)R, —N(R)S(O)2R, —N(R)R8, —NHC(═NR9)N(R)2, —NHC(═CHR9)N(R)2, —OC(O)N(R)2, —N(R)C(O)OR, —N(OR)C(O)R, —N(OR)S(O)2R, —N(OR)C(O)OR, —N(OR)C(O)N(R)2, —N(OR)C(S)N(R)2, —N(OR)C(═NR9)N(R)2, —N(OR)C(═CHR9)N(R)2, or heteroaryl, and each n is selected from 1, 2, 3, 4, or 5;
• M and M′ are independently selected from —C(O)O—, —OC(O)—, —C(O)N(R′)—, —P(O)(OR′)O—, —S—S—, an aryl group, and a heteroaryl group;
• and
• R2 and R3 are both C1-14 alkyl, or C2-14 alkenyl,
• R8 is selected from the group consisting of C3-6 carbocycle and heterocycle;
• R9 is selected from the group consisting of H, CN, NO2, C1-6 alkyl, —OR, —S(O)2R, —S(O)2N(R)2, C2-6 alkenyl, C3-6 carbocycle and heterocycle;
• each R is independently selected from the group consisting of C1-3 alkyl, C2-3 alkenyl, and H;
• and
• R′ is a linear alkyl.