Dehydro retronecine

These otonecine derivatives do not show a C8-N bond but possess a keto function at C8 and a methyl group at the nitrogen atom. Surprisingly, these seco alkaloids are of identical toxicity as the PA of type la (1,2-dehydro-retronecine and heliotridine esters). 

Pyrrolizidine ethers can be obtained by alkylation. Culvenor and Smith104 used this reaction in partial synthesis of the recently discovered alkaloids l-methoxymethyl-l,2-dehydro-8a-pyrrolizidine (158a) and 7hydroxy-1 -methoxymethyl-1,2-dehydro-8 a-pyrrolizi-dine (158b). The compounds were obtained by alkylating supinidine (157a) or retronecine (157b) with methyl iodide in the presence of... 

Retronecine 7 )3-Hydroxy-1 -hydroxymethyl-l,2-dehydro-8 -pyrrolizidine 7-Angelyl retronecine Chlorodesoxysceleratine Crispatine Fulvine Incanine Indicine Latifoline Alkaloid SC Spectabiline ... 

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