3-Hexyl-5-methylindolizidine

Z,9Z)-3-Hexyl-5-methylindolizidine (17a) from a Solenopsis sp. exhibits characteristic peaks at miz 208 (M — CH3) and 138 (M - CgHjj, a base peak) as well as a parent peak at m/z 223 in the mass spectrum. The stereochemistry has been determined by synthesis. Racemic (5Z,9Z)-3-hexyl-5-methylindolizidine (17a) was prepared by the above-mentioned methodology, using octene-1-oxide instead of butene-1-oxide (Scheme 47) (134). 

Disubstituted indolizidines, unlike many classes of amphibian alkaloids, are not unique to amphibians. 3,5-Disubstituted indolizidines such as monomorine I [(5Z,9Z)-195B] occur in ants of the genera Monomorium and Solenopsis (125,129,134). Some of the ant indolizidines are as follows (5Z,9Z)-3-n-butyl-5-methylindolizidine (monomorine I), (5Z,9Z)-3- -ethyl-5-methylindolizidine, (5Z,9Z)-3-hexyl-5-methylindolizidine, and (5 ,9Z)-3-butyl-5-(4-pentenyl)indolizidine. A series of 5-substituted indolizidines, the piclavines, were reported recently from a marine tunicate (Clavelina picta) (135). 

Three new diastereomers of 3-hexyl-5-methylindolizidine, (5Z,9Z)-, (5E,9E)- and (5Z,9 ), Fig. (8), were identified in different collections of thief ants Solenopsis (Diplorhoptrum) species from Cahfomia. The identification of these alkaloids resulted from the analysis of their MS spectra and comparison of their GC-FTIR spectra. The authors also emphasised the chemotaxonomic value of the stereochemistry of these alkaloids [23]. 

A related alkaloid, (5Z,9 )-3-hexyl-5-methylindolizidine (re/-1686), occurs in the venom of workers belonging to Solenopsis (Diplorhoptrum) species (Solenopsis molesta group).The (—)-enantiomer of this isomer was... 

Scheme 216 Synthesis of (—)-3-hexyl-5-methylindolizidine alkaloids 1686 and 1687 by Mix and Blechert. Reagents and conditions (a) Hoveyda—Grubbs catalyst (7) (5 mol %), CsHs, 75 °C (b) BF3 -OEt2 (1.25 equiv.), CH2CI2, 20 °C (c) H2, Pd/C, MeOH.

---