B-type Alkaloids

Daphnilactone B (24) was isolated as one of the major alkaloids from the fruits of three Daphniphyllum species in Japan, D. macropodum, D. teijsmanni, and D. humile, and the structure was deduced by extensive spectral analysis, as well as by chemical evidence, and finally assigned by X-ray crystallographic analysis [34,35,37]. Isodaphnilactone B (25) was isolated from the leaves of D. humile and the structure was analyzed by spectroscopic methods [30]. A zwitterionic alkaloid 26, the hydration product of daphnilactone B, was isolated from the fruits of D. teijsmanni, and the structure determined on the basis of its spectral and chemical properties [38]. 

---

Comptonim-type (Table 4, 3a) the terpenoid core is normal (taxane) and bears a 13-oxo group. The side chain however, is phenylisoserine rather than Winterstein s acid as in taxine B-type alkaloids. Comptonine (3a) and spicaledonine (8a) are the only alkaloids with a 13-oxo group where the aminoacyl moiety is not Winterstein s acid. 

A. scholaris also contains the ring-opened aspidosperma-type alkaloid, leuconolam (172), which is not present in any of the other Asian A. scholaris samples [96], It is perhaps pertinent to note that similar 6,7-seco-angustilobine B-type alkaloids have also been obtained from another Indonesian Alstonia (A. angustiloba [103] although similar compounds were not detected from an examination of the Malaysian samples. 

Daphnilactone B type alkaloids are a small group of C-14,15-seeo-yuzurimines. Most of them form a laetone between the carbonyl at C-22 and the hydroxy attached to C-21. 

Calyciphylline B type alkaloids are a group of rare C22 fused-pentacyclie yuzurimine type nor-Daphniphyllum alkaloids. Most of them eontain a six-member laetone ring. A new ealyciphylline B type alkaloid, daphlongamines H (51) was reported (Figure 13) [45]. 

Arslanian, R. L., Mondragon, B., Stermitz, F. R. and Marr, K. L. 1990. Acyl histamines and a rare protopine type alkaloid from leaves of Zanthoxylum dipetalum. Biochem. Syst. Ecol. 18 345-347. 

Tazeline-type alkaloids Galanthus sp. SiOj B + CHCl 3 + MeOH B + CHCI3 + MeOH — Identification 17... 

B. Plumeran-Type Alkaloids 1. Voaphylline-Subtype Alkaloids... 

New normal yohimbine-type alkaloids, isolated or characterized, together with their primary sources, are listed in Table I. Note that aspexcine, isolated from Aspidosperma excelsum Benth., has earlier been characterized as a 10-methoxyisositsirikine. This alkaloid, however, proved to be identical with excel-sinine (81) (53) (see Section II.B. 14.). 

Although the annelated octahydropyrrolo[2,3-b ]pyrrole unit occurs in the physostigmine-type alkaloids, simple systems were reported only in 1978. DIBAL reduction of the pyrrolidones (348) furnished the octahydropyrrolo[2,3-b jpyrrole derivatives (349 Scheme 120). It is interesting to note that LAH failed to bring about ring closure (78JOC4276). 

Berthou S, Leboeuf M, Cave A, Mahuteau J, David B, Guinaudeau H (1989) Limalongine, a Modified Hasubanan Type Alkaloid, and Clolimalongine, Its Chlorinated Derivative. J Org Chem 54 3491... 

The majority of the approaches that have been adopted for the synthesis of narciclasine (215), lycoricidine (214), and related alkaloids have involved the strategy of constructing the ring system in the order A — C —> B. There have also been examples of the A — BC and C —> A —> B type. 

Biogenetically, daphnilactone-B (36) is regarded as a plausible intermediate between daphniphylline-type and yuzurimine-type alkaloids. Thus, daphnilactone-B (36) was converted to a daphniphylline-type compound (38, mp 166-168° C22H3302N) via a bromocyanamide [39, mp (dec) 210°] and a debromocyanamide (40, mp 208-212°), as shown in Scheme V. The structure of this daphniphylline-type compound 38 was confirmed by its mass, IR, and NMR spectra coupled with von Braun degradation of 38 leading to the formation of a new... 

OCN—CH—CO—NH 1 R Schbmu II. The most characteristic fragment alkaloids ions of the amphibine-B type of... 

Biogenetically, daphtenidines A (84) and B (85) might be generated through an intermediate C from secodaphnane-type alkaloid B, followed by the formation of daphnilactone A (23) in Scheme 18.18 [85]. 

---