The total synthesis of (±)-lycoramine. Part I

Abstract

The Total Synthesis of (2)-Lycoramine. Part 1.

Amaryllidaceae Alkaloids from Lycoris radiata

“…reasons, HÀC(10b) is considered to be b-oriented, and HÀC(4a) a-oriented [18]. Subsequently, the ROESY correlation HÀC(10b)/HÀC(1) suggested the a-orientation for the OH group at C(1), and the ROESY correlations of HÀC(4a)/HÀC(4) and HÀC(4)/HÀC(2) indicated also a-orientation for both HÀC(4) and HÀC (2) (Fig.). Finally, detailed analysis of 2D-NMR data established the structure of 1 as 5,6-dehydrodihydrolycorine.…”

“…So far, more than 100 alkaloids have been isolated from Amaryllidaceae plants [10], which exhibited diverse bioacitivities, such as antiviral, insect antifeedant, antineoplastic, and acetylcholinesterase inhibitory activities [10 -14]. As part of our search for novel and bioactive compounds, we isolated three new Amaryllidaceae alkaloids, 5,6-dehydrodihydrolycorine (1), 6b-acetoxycrinamine (2), and (þ)-8-O-acetylhomolycorine a-N-oxide (3), together with eleven known analogs from bulbs of Lycoris radiata, a Chinese folk medicine famous for the treatment of poliomyelitis [15]. The new structures were elucidated by means of spectroscopic methods, and the known compounds were identified as 6-hydroxycrinamine (4) [16], homolycorine (5) [17], dihydrolycorine (6) [18], lycorine (7) [18], 7-oxodihydrolycorine (8) [19], (þ)-hippeastrine (9) [20], 2a-hydroxy-6-O-methoxyloduline (10) [21], galanthamine (11) [22], 7-deoxynarciclasine (12) [23], pancratinine C (13) [24], and 5,6-dihydrobicolorine (14) [25].…”

A new Amaryllidaceae alkaloid from the bulbs of Lycoris radiata

“…Eight known homolycorine-type alkaloids (3)(4)(5)(6)(7)(8)(9)(10) were also isolated and identified as trispherine (3) [14] , 8-O-demethylhomolycorine (4) [16] , homolycorine (5) [17] , 9-O-demethylhomolycorine (6) [18] , oduline (7) [19] , lycorenine (8) [20] , 6α-O-methyllycorenine (9) [21] , O-ethyllycorenine (10) [22] by comparison of their 1D-NMR data with those in the literature. All of the alkaloids were evaluated for inhibitory activities against flu virus A in vitro [23] , and alkaloids 1-3 showed weak antiviral activities with IC 50 values of 2.06, 0.69 and 2.71 μg·mL −1 , and CC 50 values of 14.37, 4.79 and 80.12 μg·mL −1 , respectively.…”

Electrophilic C12 Building Blocks for Alkaloids: 1,1 Iterative Organoiron‐Mediated Routes to (±)‐Lycoramine and (±)‐Maritidine

“…There has been considerable attention paid to the development of synthetic routes to lycoramine [27] and galanthamine, [28] and since Martin and Garrison's short route [29] to lycoramine from o-vanilin, there have been significant advances [30,31,32] but only quite recently has the first enantioselective synthesis been reported. [33] Typically, the methods now preferred for the direct construction of the quaternary centre use palladium catalysed [31,34] or radical [35,36] cyclisations to alkenes, but an unusual photochemical intramolecular cyclisation of an activated arene to cyclohexenone has also provided a highly original basis for a total synthesis.…”