Table 1. Selected torsion angles (°).

Isomer	Chiral center	Atom chain	Torsion angle
S	C5	N1—C6—C5—C4	104.4 (2)
S	C5	N1—C6—C5—C7	−149.53 (17)
R	C2	O1—C1—C2—C3	−103.9 (2)
R	C2	O1—C1—C2—C7	152.42 (18)
R	C2	O1—C1—C2—C8	20.6 (3)
R	C15	N4—C16—C15—C17	−104.6 (2)
R	C15	N4—C16—C15—C14	148.82 (17)
S	C13	O2—C12—C13—C18	107.0 (2)
S	C13	O2—C12—C13—C14	−148.48 (18)
S	C13	O2—C12—C13—C19	−18.6 (3)