Benzylisoquinoline alkaloids isoquinoline

C-9, and C-10, always with a phenolic hydroxy group at the 8a position. Moreover, they differ from one another by the oxidation state of the benzylic C-13 as well as by substitution and degree of saturation of the isoquinoline fragment. These alkaloids, classified as benzylisoquinoline alkaloids (2,70-74), have recently been called by Shamma et al. (75-77) pseudobenzyliso-quinolines originating from protoberberine alkaloids. In Table V a list of 8,8a-secoberbine alkaloids, sources, and spectral data are presented. 

The synthesis of the basic skeleton of 1-benzylisoquinoline alkaloids has been reported by Uff et al. 15) starting from isoquinoline and benzyl chloride (Scheme 5). The preparation of Reissert compound iV-benzyl-l-cyano-l,2-di-hydroisoquinoline (4) was performed in a dichloromethane-water two-phase system with potassium cyanide and benzoyl chloride in about 64-69% yield. The deprotonation of 4 with sodium hydride in dimethylformamide solution, the subsequent alkylation with benzyl chloride, and the final alkaline hydrolysis could be performed as a one-pot reaction sequence to supply 1-benzylisoquinoline (25) in an overall yield of 75-84%. 

The isoquinolines 70 are an important subclass of the tertiary N-benzylamides, and their lithiation and benzylation is an important way of synthesising a range of benzylisoquinoline alkaloids.4849... 

MAO was used in vivo and in vitro as a catalyst for the production of norlaudano-sine from dopamine (Fig. 16.7-14)[35]. Norlaudanosine is an important synthon for benzylisoquinoline alkaloids, providing the upper isoquinoline portion of the morphinan skeleton. In vitro and in vivo yields were in the range of 20 %. 

Dolejs and Slavik reported the mass spectrometric fragmentation of methines of the benzylisoquinoline alkaloids (379). The isoquinoline and... 

Comparatively few simple isoquinoline alkaloids have been found to occur naturally. Until now such compounds have been encountered in three or four species of the Cactaceae, in a Chenopodiaceae [Salsola arbuscula Pall. (S. richteri Karel)], in three species belonging to the family of the Fumari-aceae [Corydalis pallida (Thunb.) Pers.,C. awrea Willd., C. tvherosa DC.] and in one Papaveraceae Papaver somniferum L.). While no doubt exists as to the native occurrence of the anhalonium and salsola isoquinolines, hy-drohydrastinine and hydrocotarnine may have been artifacts from the benzylisoquinoline alkaloids of Corydalis tuberosa and Papaver somniferum. 

A second major structural type, commonly known as benzylisoquinoline (BIQ) or tetrahydrobenzylisoquinoline (TBIQ), alkaloids constitute one of the two most numerous types of alkaloids. As is true for the simple isoquinoline alkaloids mentioned above, all are derived from a 3,4-dihy-droxytyramine (dopamine) precursor condensed with a carbonyl compound. In this case, the precursor of most, if not all, benzylisoquinoline alkaloids is 4-hydroxyphenylacetal-dehyde. Benzylisoquinoline alkaloids are found in a limited group of plant families some have great medical impor-... 

Isoquinoline alkaloids are derived from tyrosine through the intermediacy of 3,4-dihydroxyphenylethylamine (dopamine) and a carbonyl unit of various origins. The genesis of tyramine, and dopamine from tyrosine has been described previously (see Chapter 28). In contrast to benzylisoquinoline alkaloids (see below), the formation of isoquinoline alkaloids usually involves the amine and an a-ketoacid instead of an amine and aldehyde. However, several compounds can... 

Other families known to possess isoquinoline alkaloids include the Alangiaceae, Chenopodiaceae (a family related to the Cactaceae), Fabaceae, Musaceae, Nymphaeaceae, and Sterculiaceae (Lundstrom, 1983). At least four species of the Chenopodiaceae contain isoquinoline alkaloids, whereas other species contain P-phenylethylamines. Many of the plants that contain benzylisoquinoline alkaloids also contain smaller amounts of isoquinoline alkaloids. Among these are plants belonging to the Annonaceae, Euphorbiaceae, Fuma-riaceae, Hemandiaceae, Menispermaceae, Monimiaceae, Papaveraceae, Ranunculaceae, and Rhamnaceae (Lundstrom, 1983). The distribution of benzylisoquinoline alkaloids is discussed in more detail below. 

Benzylisoquinoline alkaloids differ from isoquinoline alkaloids in that a different carbonyl donor unit, 3,4-dihydroxy-phenylacetaldehyde (19), is involved in their biosynthesis (Herbert, 1988 Schumacher et al., 1983). The plants that contain benzylisoquinoline alkaloids often are poisonous see references in Chapter 1 and Kingsbury, 1964). At least 4000 benzylisoquinoline alkaloids belonging to many subgroups are known (Figs. 32.5 and 32.6) (Verpoorte et al., 1991 Waller and Nowacki, 1978). 

The simplest alkaloids of this series are those in which the nitrogen-containing ring of the isoquinoline system is completely saturated (Fig. 32.7). Quaternary bases also are found. Tetrahydrobenzylisoquinoline alkaloids are widespread and are found in almost all the families that possess benzylisoquinoline alkaloids. About 100 alkaloids of this type are known (Guinaudeau and Bruneton, 1993). 

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