Other Natural Simple Isoquinolines

The derivatives of the synthetic oily base were identical with those of naturally occurring carnegine and pectenine. Furthermore, the possible alternate structure (the product of ring closure in o-position to one of the methoxy groups) was excluded by the observation that permanganate oxidation of the dihydro compound gave m-hemipinic and not hemipinic acid. 

Schopf and Bayerle (31) obtained norcarnegine under mild ( physiological ) conditions (pH 5, at 25°) by condensing hydroxytyramine with acetaldehyde. 

Nakada and Nishihara (51) synthesized carnegine by suspending veratryl-acetoxime in toluene and treating with POCI3, obtaining 1-methyl-6,7-dimethoxy-3,4-dihydro-isoquinoline. Catalytic reduction of the methyl methosulfate of this compound yielded carnegine. 

These alkaloids are not cactus alkaloids, but their structure reveals a surprising analogy with carnegine. Actually, carnegine is OjA -dimethyl-salsoline. 

Salsoline and salsolidine (0-methylsalsoline) have been found by Orekhov and Proskurnina (32-35, 36, 37) in the desert plant Salsola arbuscula (S. richteri) belonging to the family Chenopodiaceae. A third alkaloid, of unknown constitution (salsamine), occurs in traces in the drug. 

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Obviously, under these conditions, it will be quite possible to find bases of the same type in plants of widely separated botanical families or even in products of animal metabolism. The individual cactus alkaloids will be found, therefore, under the headings /8-Phenethylamines (see Vol. Ill, chap. 22) and Simple Isoquinoline Alkaloids (see Vol. IV, chap. 26), where are also included all other natural bases of similar structure but different origin. 

For this book to serve as a completely satisfactory reference, it must be structured so that a reader who comes to it with one specific word in mind that is related to the simple, natural isoquinolines, can immediately locate all other related entries. Total cross-referencing is needed. As a way to simplify this type of search, the main part of this book is actually a collection of three indices. Each index is arranged alphabetically, very much like a dictionary. The first index lists the common trivial names, the second lists the structures of the compounds themselves and the plants that contain them, and the third lists the taxonomic names of these plants and the compounds that have been found in them. 

The early chapters introduce generally simple single-ring heterocycles and other compounds which serve as models for the more complex structures. The isoquinoline alkaloids and indole alkaloids are particularly noteworthy in terms of both the wealth of structural variations and the extent of cmr data available. The fact that these two groups of natural products, along with some... 

Since heteroaromatic compounds sometimes exhibit interesting physical properties and biological activities, construction of substituted heteroaromatics has drawn some attention. Heteroaromatics can be divided into two major categories. One is the tt-electron-sufhcient heteroaromatics, such as pyrrole, indole, furan, and thiophene those easily react with electrophiles. The other is the 7r-electron-deficient heteroaromatics, such as pyridine, quinoline, and isoquinoline those have the tendency to accept the nucleophilic attack on the aromatic ring. Reflecting the electronic nature of heteroaromatics, the TT-electron-deflcient ones are usually used as the electrophiles.t The rr-electron-sufficient heteroaromatics having simple structures, such as 2-iodofuran and 2-iodothio-phene, have also been utilized as the electrophiles. Not only the electronic nature of the heteroaromatics but also coordination of the heteroatom to the palladium complexes influence catalytic activity. This is another reason why the couphng reaction did not proceed efficiently in some cases. 

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