Alkaloids pepper

The preparation of a special chapter in this series on the constituents of pepper (6) led us to ignore pepper alkaloids. After publication of the chapter, we discovered that it dealt with the alkaloids of red pepper species (Capsicum, So-lanaceae), which are not pyrrolidines, and the purpose of this addendum is to provide a survey of the pyrrolidine alkaloids contained in black pepper species Piper, Piperaceae. 

The total syntheses of these pepper alkaloids are not those of pyrrolidines but rather syntheses of their acid parts. Thus dihydrowisanidine (137) has been prepared by a series of reactions, the key step of which is the formation of the carbon-carbon double bond by a Wittig-Homer reaction (217, 218). Schemes 41 and 42 summarize two syntheses of okolasine from sesamolmethyl ether (279) of course, routes to okolasine also yield the corresponding piperidine alkaloid wisanine. Molybdenum-catalyzed elimination of allylic acetate (149) yielded (E,E)-diene ester 150 en route to trichonine (220) worthy of note is the use of an aluminum amide in the preparation of amide 143 from ester 150 (Scheme 43). 

In addition to the amides responsible for the sharp taste of peppers, alkaloids of various types including aporphines have been found in the family. 

Piplartine (3), another pepper alkaloid, is dimerised on irradiation with ultraviolet light to the compound (4), which occurs as a natural product in its ov/n right - as an extractive from P. tuberculatum (R.B.-Filho, M.P. DeSouza and M.E.O. Mattos, Phytochem., 1981, 20, 345). 

In the pepper alkaloid group, several new amides have been isolated from Achillea spp. One of them, from A, biebersteinil Afan, is the piperideide(19)Others include (20) (from A. ly caonica Boiss, et Heldr.), and the hitherto structurally unencountered acetylenic amides (21) and (22) (from A. spinulifolia Fenzl ex... 

Syntheses of a variety of naturally occurring polyene and polyenyne amides have been reported. Pepper alkaloids have been obtained using the Wittig reaction and phosphonate, e.g., (167), - routes. 

Cuscohygrine has been isolated for the first time from the roots of Solanum carolinense. The guinea pepper alkaloid okolasine, which is the pyrrolidine amide (1) of 6-methoxypiperic acid, has been synthesized by the standard procedure of reaction of the acid chloride with pyrrolidine. The acid was reached by two routes from 2-methoxy-4,5-methylenedioxybenzaldehyde. ... 

Zsila F, Hazai E, Sawyer L. Binding of the pepper alkaloid to bovine beta-lactoglobulin Circular dichroism spectroscopy and molecular modeling study. J AgrFood Chem 2005 53(26) 10179-85. 

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