Alkaloids benzyltetrahydroisoquinoline, modifie

Alkaloids Derived from Tyrosine Modified C Benzyltetrahydroisoquinoline Alkaloids ... 

The 1-benzyltetrahydroisoquinoline skeleton is one of preeminence in the elaboration of plant alkaloids. Only the terpenoid indole skeleton (Section 6.6.2) appears in more diversely modified form. Among the benzylisoquinolines, reticuline (6.127) is of outstanding importance as a substrate for modification. Formation of the... 

The 1-benzyltetrahydroisoquinoline skeleton is a very important one in the field of plant alkaloids and is the subject of various, interesting modifications. Indeed, with the exception of terpenoid indole alkaloids, no other skeleton is so diversely modified. In this family of benzylisoquinolines, reticuline (25) is preeminent, being a key intermediate in the biosynthesis of many alkaloids. 

The condensation of dopamine (4) with phenylethyl units and subsequent cyclization result in the formation of benzyltetrahydroisoquinoline alkaloids. These initial reaction steps are identical to those discussed for the formation of simple tetrahydroisoquinoline alkaloids. However, the additional aromatic ring allows further modification, and a variety of structurally diverse classes of alkaloids are obtained via different aryl-aryl coupling reactions. Among others, protoberberine alkaloids, porphine alkaloids, and the most important class of opium alkaloids can be summarized as modified benzyltetrahydroisoquinoline alkaloids. 

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