Lycorenine alkaloids

Alkylation of 2-lithio-2-ethoxycaibonyl-1,3-dithiane with 5-bromo-l,2-pentadiene gave a precursor for the total synthesis of lycorenine alkaloids. ... 

Lycopodium spp., alkaloids, 752 pharmaeological action, 755 Lycoramine, 406, 408 Lycorenine, 406, 409 Lycorine, 389, 406... 

L-phenylanine alkaloids alkaloids Crinine Eloramultine Galanthamine Galanthine Haemanthamine Lycorine Lycorenine Maritidine Oxomaritidine Vittatine... 

A number of spectroscopic studies have been completed, and 13C-NMR spectroscopy continues to be a useful analytical tool for structural elucidation. Furthermore, CD spectroscopy has proved to be an effective means for providing stereochemical information for the lactone alkaloids of die lycorenine class (33). 

The conversion of lycorine (1) into the [2]benzopyrano[3,4-g]indole alkaloid hippeastrine (101) was completed according to the criteria previously developed during the transformation of caranine (2) to lycorenine (102) (Vol. XI, p. 342). Thus cyanogen bromide reacted... 

The X-ray analysis of lycorenine methiodide has established the a (steroid notation) configuration of the hydroxy group at position 7. From considerations of the specific and molecular rotations of analogous hemiacetal and lactonic alkaloids it has been inferred that oduline (109), nerinine (99), krigeine (105), unsevine (112), and krigmamine (104) all possess an a-hydroxy group at position 7 (20). 

A definite picture of the biosynthesis of norpluviine (10), the key intermediate to the pyrrolophenanthridine, and the lycorenine-type alkaloids was derived from two sets of feeding experiments. 

The observation79 in an earlier more extensive study that norpluviine (100) is a precursor for lycorenine (102) has been confirmed.80 Incorporations were also recorded with both norpluviine (100) and pluviine (101) for other alkaloids of related structure to norpluviine, including galanthine (103). Although radio-active narciclasine (96) was also isolated in the experiment with norpluviine, its known derivation76,81 by way of a different pathway through vittatine (93) indicates that this is not significant. 

Lycorenine-type alkaloids derived from [2]benzopyrano [3,4g]indole) including both lycorenine and homolycorine ... 

Representative examples of Amatyllidaceae alkaloids are lyeorine 1, lycorenine 2, crinine 3, cheiylline 4, galanthamine 5, montanine 6, nareielasine 7, and tazettine 8. 

The molecular structures and absolute configurations of two 5,10-ethano-phenanthridine alkaloids, 6-hydroxybuphanidrine (22) methiodide and haeman-thamine p-bromobenzoate (23), have been determined by J -ray analysis.19 An important first paper on the 13C n.m.r. spectral analysis of several Amaryllidaceae alkaloids (among them buphanamine, lycorenine, tazettine, deoxy-tazettine, montanine, and galanthine) using sophisticated proton decoupling techniques requires the careful attention of alkaloid chemists.20 The XH n.m.r. 

From a detailed examination of the reduction and acetylation products of lycorenine, Kondo and Ikeda (116) suggested that the partial formula (XIX) for the alkaloid he expanded to LXXXI. Their interpretation of the experimental data in terms of this structure was, at times, most tenuous. Particular difficulty was encountered in rationalizing the formation of an 0-heterocychc ring upon hydrogenation of lycorenine, since such a step required preferential hydrogenation of the... 

The position of the unsaturation in lycorenine and homolycorine has been assigned by indirect methods. Since the double bond is stable to lithium aluminum hydride and two isomers are produced by catalytic hydrogenation, 2,3- or 4,5-unsaturation is unlikely. The ultraviolet spectra of the alkaloids eliminate the conjugated positions 5a,lib and 11b,11c. Unsaturation at 5,5a is untenable since deoxylycorenine does not have the properties of an enol ether. Of the two remaining positions,... 

A comparison of the molecular rotations of lycorine and 2-epilycorine provided the first evidence for the absolute configuration of alkaloids of the lycorine type by the application of Mills rule. The development of suitable chemical methods of interconversion between the lycorine- and lycorenine-type alkaloids permitted an additional correlation between the two types by the Hudson-Klyne lactone rule. These assignments have recently been shown to be correct by X-ray crystallographic methods (65). With these findings the structure and absolute configuration of lycorine is described by I (R, Ri = H). The absolute configurations of many of the alkaloids discussed in Section III also are secure because these alkaloids have been interrelated and converted to known compounds of the lycorine series. 

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