Delphinifoline: a lycoctonine alkaloid with configuration 1α-OH

Abstract

functional group at C(7) established delphinifoline as a member of the lycoctonine family of alkaloids. The a configuration observed at C(1)is unexpected and calls into question the structural assignments of all alkaloids of this class.

The lycoctonine family of alkaloids: a stereochemical revision

“…lc. They are similar to those found in other aconitine and lycoctonine type alkaloids in which the boat form of the ring A is stabilized by the intramolecular hydrogen bonding (20)(21)(22)(23)(24)(25). The projection of the structure is shown in Fig.…”

Structure and conformation of aconitine

“…At biological pH the N atom in aconitine would be protonated which would permit formation of either an intramolecular hydrogen bond as in jesaconitine (A ring in boat form) or a hydrogen bond with the receptor having the A ring in a chair form thus exposing the N atom. Torsion angles have been tabulated (5) for six other C19 diterpenoid alkaloids (Codding & (6) Kerr, 1981;Kerr & Codding, 1982); these exam-(5) inations have established that there is a high degree of among the substituents on ring D has the net effect of flattening the boat form at C(15) as demonstrated by the smaller torsion angles around C(15) in aconitine: C(13)-C(16)-C(15)-C(8) 18.7 (9) and C(16)-C(15)-C (8)-C (9) -19.9 (8)°. Torsion angles have been tabulated (5) for six other C19 diterpenoid alkaloids (Codding & (6) Kerr, 1981;Kerr & Codding, 1982); these exam-(5) inations have established that there is a high degree of among the substituents on ring D has the net effect of flattening the boat form at C(15) as demonstrated by the smaller torsion angles around C(15) in aconitine: C(13)-C(16)-C(15)-C(8) 18.7 (9) and C(16)-C(15)-C (8)-C (9) -19.9 (8)°.…”

“…Table 4 contains the torsion angles for the various rings in aconitine. These angles, averaged over the six structures reported in Codding & Kerr (1981) and Kerr & Codding (1982), are 25.4 and 22.8 ° respectively. These angles, averaged over the six structures reported in Codding & Kerr (1981) and Kerr & Codding (1982), are 25.4 and 22.8 ° respectively.…”