SYNTHESIS OF PYRROLIZIDINE OXIME-222 AND OXIME-236 - NOVEL ALKALOIDS OF A DENDROBATID POISON FROG

The structures of two novel spiropentanopyrrolizidine oxime alkaloids, namely spiro[cyclopentane-1,1'-[1H]-pyrrolizine]-7'-oxime (1) and 2', 3',5',6',7',7a'-hexahydro-2,2-dimethylspiro clopentane-1,1'-[1H]pyrrol izine]-7'-oxime-O-methyl ether (2) have been confirmed by synthesis. T he route involved synthesis of nitropolyzonamine (4), a known milliped e alkaloid, from 2,2-dimethylcyclopentanone in 6 steps. After conversi on of 4 to the ketone 6, the oxime 1 and O-methyl oxime 2 were obtaine d. The relative stereochemistry of synthetic nitropolyzonamine was con firmed by x-ray crystallography.