without changing your settings we'll assume you are happy to receive all RSC cookies.
You can change your cookie settings by navigating to our Privacy and Cookies page and following the instructions. These instructions
are also obtainable from the privacy link at the bottom of any RSC page.
The mode of incorporation of 2H-labelled putrescines into the rosmarinecine (14) portion of the pyrrolizidine alkaloid rosmarinine (15) in Senecio pleistocephalus plants has been established by 2H n.m.r. spectroscopy. The use of [1,1,4,4-2H4] putrescine (16) dihydrochloride produced rosmarinine (18) with 2H labels mainly at C-3α, C-3β, and C-9pro-S. Rosmarinine (22) derived from [1,1-2H2]putrescine (19) dihydrochloride showed the same 2H n.m.r. spectroscopic signals plus others for C-5α, C-5β, and C-8. These labelling patterns are interpreted by the intermediacy of homospermidine (6) in the biosynthetic pathway and by the existence of 2H isotope effects. Feeding experiments with (R)-[1-2H]-(23) and (S)-[1-2H]putrescine (26) dihydrochloride gave a sample of rosmarinine (25) with 2H present at C-3β, C-5α, C-8α, and C-9pro-S from the former precursor, and a sample (28) with 2H present at C-3α and C-5β from the latter precursor. These patterns are consistent with oxidation of three of the four amino groups involved in the conversion of two molecules of putrescine into 1β-formyl-8α-pyrrolizidine (12) with stereospecific loss of the pro-S hydrogens. Reduction of the 1-formylpyrrolizidine (12) to isoretronecanol (13) takes place by attack of a hydride donor on the C-re face of the aldehyde group. Use of [2,2,3,3-2H4]putrescine (29) dihydrochloride gave rosmarinine (30) labelled with 2H at C-1α, C-2β, C-6α, C-6β, and C-7α. Feeding experiments with (R)-[2-2H]-(31) and (S)-[2-2H]-putrescine (33) dihydrochloride gave rosmarinine (32) labelled with 2H at C-2β and C-6α from the former, and rosmarinine (34) with 2H present at C-1α, C-6β, and C-7α from the latter precursor. Formation of the pyrrolizidine ring involves stereospecific removal of the pro-R hydrogen and retention of the pro-S hydrogen on the carbon destined to become C-1 of rosmarinecine, and hydroxylation at C-2 and C-7 of isoretronecanol (13) therefore proceeds with retention of configuration to form rosmarinecine (14).
Fetching data from CrossRef. This may take some time to load.
Journal of the Chemical Society, Perkin Transactions 1
- Information Point
This text is added as a work around for heading error in Accessibility testing