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A series of enantiomerically pure C8cC15 monoseco analogues, 2330, of the alkaloids cryptopleurine (1) and julandine (2) have been prepared using cinnamyl chloride 37 and (S)- or (R)-2-methylpiperidine as key building blocks. Two related compounds, 31 and 32, have also been synthesized. Each of these analogues has been subjected to various biological evaluations and most of them show dramatically reduced cytotoxicity compared with parent system 1. Nevertheless, they are potent anti-angiogenic agents. The formation and single-crystal X-ray analysis of the spirocyclic dienone 54, a by-product arising from attempts to prepare analogue 32, is also described.

Four enantiomerically pure monoseco-analogues, 5, 7, 9, and 11, of the phenanthroquinolizidine alkaloid julandine (1) and four of congener cryptopleurine (2), viz. compounds 6, 8, 10, and 12, have been prepared and subjected to preliminary biological evaluation. These analogues show dramatically reduced cytotoxicity compared with the parent system 2 but they are, nevertheless, potent anti-angiogenic agents.

Two novel analogues, 2 and 3, of the C-riboside showdomycin (1) have been prepared by exploiting the N-TIPS-substituted pyrrole 7 as a synthetic equivalent for the maleimide C3 anion. The tetraacetate precursor, 12, of target 2 as well as target 3 itself