Phenethylisoquinoline autumnaline

These alkaloids have a phenyl or phenylpropyl nucleus. The group includes simple phenyl amine (tyramine, hordenine), catecholamine (dopamine, noradrenaline, adrenaline), simple tetrahydroisoquinoline (mescaline, anhalamine, anhalonine, anhalonidine), benzylisoquinoline (e.g., papaverine), phthalideiso-quinoline (e.g., noscapine), phenethylisoquinoline (autumnaline, floramultine and kreysigine), tetrahydroisoquinoline (emehne and cephaeline) and terpenoid tetrahydroisoquinoline (secologanin and ipecoside) alkaloids. 

The simple phenethylisoquinoline alkaloid autumnaline (68), isolated from Colchicum cornigerum (2), has the basic skeleton of several phenethylisoquinoline alkaloids described later. The structure of 68 was arrived at through comparison with a synthetic sample (2a, 2b). 

Simple Phenethylisoquinolines.—The alkaloid (—)-autumnaline (210) from Colchicum cornigerum (Liliaceae, subfamily Wurmbaeoidae) possesses the absolute configuration shown, and its synthesis has been carried out. ... 

Alkaloids are not limited to those natural products which are basic in character. For example, colchicine isolated from Colchicum autumnale (Ldiaceae) and used for the treatment of gout, etc. is not basic because the nitrogen atom in the molecule is present in a neutral amide group. However, the biosynthetic precursor of colchicine is autumnaline, a typical, basic phenethylisoquinoline alkaloid. Therefore any compound derived from such an intermediate should be classified as an alkaloid. 

Autumnaline is a phenethylisoquinoline alkaloid, and possesses an additional Cj unit compared with the benzylisoquinoline alkaloids. Autumnaline, postulated to be the biosynthetic precursor of colchicine, was isolated from Colchicum cornigerutn (Colchicaceae) [4]. O-methylandrocymbine is formed through the intramolecular -oxidative phenolic coupling... 

To date, only one naturally occurring phenethylisoquinoline alkaloid is known, namely autumnaline, isolated from Colchicum cornigemm (Schweinf.) Tackh. et Drar. (Liliaceae). However, some interesting chemistry on synthetic bases of this type has been discussed. " ... 

As mentioned above, the only known naturally occurring monomeric phenethylisoquinoline alkaloid is autumnaline. There is also one fully characterized, naturally occurring bisphenylisoquinoline, namely, (—)-melanthioidine. Very recently, the new alkaloid yolantinine (jolantinine) was obtained from Merendera yolantae E. Czerniak (Liliaceae), and was assigned the structure shown below. ... 

Alkaloid anti-inflammatory agent autumnaline colchicine Colchicum double haploid elicitors in vitro culture phenethylisoquinoline polyploid... 

The crucial test for the hypothesis lay in the examination of compounds of type 6.171) and 6.173) as colchicine precursors. In the event [119-121], 0-methylandrocymbine 6.172) was a spectacularly good precursor for colchicine. The phenethylisoquinoline 6.171), called autumnaline, was also clearly implicated in biosynthesis only the (5)-isomer of autumnaline, with the same absolute configuration as colchicine is involved, and oxidative coupling of this base occurs in a para-para sense rather than the alternative, ortho-para. Results of other experiments, together with those discussed here, led to the pathway illustrated in Scheme 6.34. 

Several genera of the Liliaceae plant family have been identified to produce the secondary metabolite autumnaline (45), which also serves as key intermediate in the biosynthesis of a variety of phenethylisoquinoline alkaloids (see Schemes 12.9 and 12.10). Colchicine (54), derived from autumnaline (45) via a remarkable ring-expanding rearrangement, is the most prominent member of this class of tyrosine-derived alkaloids. 

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