Narcissus and Daffodil

Figure 6.14 Mass fragmentation pattern of homolycorine (23).
Alkaloids of Narcissus 181
A further general and noteworthy feature is the low abundance of the molecular
ion in all compounds with a double bond ∆ 3,4 (Schnoes et al., 1968).
Crinine-haemanthamine types
Several general considerations should be taken into account for these types of
alkaloids:
1 The stability of the molecular ion, which is almost always the base peak.
2 The important role played by the aromatic ring in the stabilisation of the ions,
which is retained in all fragments of high mass while the nitrogen atom is often
lost.
3 The relatively large number of nitrogen-free ions.
4 The fragmentation mechanisms are initiated by the rupture of a bond β to the
nitrogen atom which implies the opening of the C-11/C-12 bridge (Longevialle
et al., 1973a,b).
(a) Compounds with a saturated ring C and no bridge substituent.
The configuration of the substituent on ring C plays a minor role in the fragmentation
process.
(b) Compounds with a double bond (∆ 1,2 ) in ring C and no bridge substituent.
The fragmentation pattern involves ruptures of C-4a/C-10b and C-3/C-4
bonds. A characteristic feature is the loss of a nitrogen-containing moiety,
C3H5N [M-55].
(c) Compounds with a double bond (∆1,2 ) in ring C and a hydroxyl substituent at
C-11.