Amaryllidaceae, muscarine, imidazole, oxazole, thiazole and peptide alkaloids, and other miscellaneous alkaloids

Chapter 3 Chemical and Biological Aspects of Narcissus Alkaloids

“…The history of the Amaryllidaceae alkaloids, their structural elucidation, and their biological profiles, as well as their synthesis, have been summarized on several occasions (20,33,(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48) which, together with the regular publications in the journal Natural Product Reports (34,(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66), represent a valuable source of information.…”

“…For that reason, the presence of these alkaloids is a distinctive feature of the Narcisseae tribe. The main groups of alkaloids originating from a para-para oxidative phenolic coupling of O-methylnorbelladine (87) (hemanthamine, tazettine, and narciclasine types) are frequently represented in this genus by the model alkaloid of each group, hemanthamine (53), tazettine (62), and narciclasine (68), respectively. An exceptional homolycorine-type alkaloid is dubiusine (33), which has an unusual hydroxybutyryl substituent (72).…”

“…Tazettine (62) is a widely reported alkaloid in the Amaryllidaceae family, particularly in Narcissus (see Tables VIII and IX), although it is known to be an extraction artifact of pretazettine (64) (75). All the alkaloids of the tazettine type that are isolated from Narcissus species show the typical methylenedioxy group between the C-8 and C-9 positions.…”

Reactions of Dimethyl Acetylenedicarboxylate with 2,5-Dithiobiurea Derivatives

“…16 The one-pot, pseudo-five-component synthesis of bis[2-(arylimino)thiazolidin-4-ones] has also been reported. 17 Recently, it has been reported that, upon heating or by using microwave irradiation, 1,6-disubstituted 2,5-dithiobiureas 1a-c react with dimethyl acetylenedicarboxylate 18a (2) in methanol to give methyl 7-oxo-1,3-bis(imino)-3,7-dihydro-1H-pyrazolo [1,2-c] [1,3,4]thiadiazole-5-carboxylates 5a-c (Scheme 1) 18b in 76-79% yield. Scheme 1 Reported formation of 1H-pyrazolo [1,2-c] [1,3,4]thiadiazole-5-carboxylates 5a-c from reaction of 2,5-dithiobiureas 1 with dimethyl acetylenedicarboxylate (2) In addition, it was reported that reaction of 1a with 2 also resulted in a different compound class namely the dimer 3a (along with some other isomers 7a and 8a, see below).…”

Two New Alkaloids of the Crinane Series from Pancratium sickenbergeri

“…The known alkaloids isolated were identified as haemanthamine (2) [11], norgalanthamine (3) [16], haemanthidine (4) [17], vittatine (5) (16), 11-hydroxyvittatine (6) [18], pancracine (7) [19], and lycorine (9) [18], by comparison of their physical and spectroscopic data with literature data.…”