Macrocyclic Pyrrolizidine Alkaloids From Crotalaria Rosenii

Crotolaria rosenii, family Leguminosae, is a poisonousrnendemic shrub or small slender tree found inrnIaountain scrub and forest clearings between 2000 and 3000rnm. The powderod leves and flowers of C. rosenii wererndefatted with petroleum ether (60-800 C), extracted 'lithrnr~ethanol (soxhlet) and subjected to acid-base extractionrnto give a raw basic extract containing nine alkaloids.rnColumn chromatogr2.phic separn.tion of the raw extract onrnsilica gel with chloroform-methanol mixture resulted inrnthe isolation of three alkaloids. The structures ofrnthese alkaloids were determined by 2-dimensional nuclearrnwagnetic resonanco techniques as well as mass and infraredrnspectra. The three alkaloids were identified as madurensinG,rn7-acetyl maclurensine and Crotaflorine.rn11pplication of homo and hetero nucleHl.' shift correlationsrnhave enabled unequivocal assignments of the carbonrnchemical shifts of these compounds and pointed out erraneousrnconclusion made by other workers.

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