Stemofoline

Stemofoline is an insecticidal alkaloid produced in the leaves and stems of the plant Stemona japonica. It has a good spectrum of activity, with rapid action, and is a potent agonist of the nicotinic acetylcholine receptor in insects. These features make it a promising lead, except that its highly complex polycyclic structure is a real challenge for synthesis (Figure 3). 

In an approach to stemofoline the elaboration of the tricyclic system involves generation of a 1,3-dipolar species from a vinylogons A -trimethylsilylmethyl amide. The design also provides a proper dipolarophile. ... 

Stemona alkaloids. Root extracts of the medicinal plants Stemona japonica and S. tuberosa (Stemona-ceae) have been used in Chinese and Japanese folk medicine as insecticides, anthelmintics, and as drugs for the treatment of tuberculosis, bronchitis and pertussis. Responsible for the activities is a group of more than 20 polycyclic alkaloids with diverse structures, e.g. protostemonine CjsHsiNOj, Mr 417.50, mp. 172-173 °C, [alD +148° (CH3OH) and stemofoline. 

Alkaloids of the roots of plants of the Stemonaceae have insecticidal activity. Several alkaloids have been isolated from the root extracts that have been used to eradicate zooparasites from man and agricultural animals. Among these are stemospironine (13), stemofoline (14), and stemonine (15) (Fig. 29.4) (Sakata et al., 1978). 

There are also several examples of imidate-derived azomethine yhdes reported in the Hterature. For example, the Gin group described a clever use of these 1,3-dipoles in an approach to the azatricychc core of some stemofoline members of the stemona alkaloid family. The formation of the azomethine ylide 164 occurred upon exposure of pyrroUdine 163 to triflic anhydride and tetrabutylammonium triphenyldifluorosihcate (TBAT Scheme 35) (2008T3629). Cycloaddition of the resulting dipole across the pendant vinyl sulfide fiomished 165 in 71% yield. Enol triflate 165 was then reduced to give the saturated side chain in 166 in 89% yield by the action of Pd/C under an H.2 atmosphere. The enolate derived from 166 was treated with ethyl iodoa-cetate in the presence of hexamethylphosphoramide (HMPA) followed by... 

Pyrido[l,2-a]azepines stemofoline. Stemona curtisii. NACE-MS 50 mM ammonium acetate, 1 M ESI-MS [77]... 

The stemofoline group comprises some of the structurally more complex representatives of the Stemona alkaloids, and currently ten alkaloids have been described stemofoline (48) 17,22,53,54), oxystemofoline (49) (77), methoxystemofline (50) (77), 2 -hydroxystemofoline (51) 22,36), 16,17-didehydro-16( )-stemofoline (52) 22,54), also named as didehydrostemofoline, l, 2 -didehydrostemofoline or asparagamine A (5,55),... 

The absolute configuration of stemofoline (48) was established by X-ray analysis of its hydrobromide monohydrate (heavy-atom method) (5i), while the alkaloids oxystemofoline (49) and methoxystemofoline (50) had their relative configurations assigned after 2D-NMR studies (77). 

H- and C-NMR data (Table XVII and Table XVIII, respectively) have been reported for stemofoline (48), oxystemofoline (49), 2 -hydroxystemofoline (51), and... 

Stemofoline type Stemona alkaloids Occurrence and Properties. 

H-NMR Chemical Shifts (5, ppm) and Coupling Constants (/, Hz) for the Stemofoline Alkaloid Group. 

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