103616-00-8Relevant articles and documents
An efficient synthesis of loline alkaloids
Cakmak, Mesut,Mayer, Peter,Trauner, Dirk
supporting information; experimental part, p. 543 - 545 (2012/04/04)
Loline (1) is a small alkaloid that, in spite of its simple-looking structure, has posed surprising challenges to synthetic chemists. It has been known for more than a century and has been the subject of extensive biological investigations, but only two total syntheses have been achieved to date. Here, we report an asymmetric total synthesis of loline that, with less then ten steps, is remarkably short. Our synthesis incorporates a Sharpless epoxidation, a Grubbs olefin metathesis and an unprecedented transannular aminobromination, which converts an eight-membered cyclic carbamate into a bromopyrrolizidine. The synthesis is marked by a high degree of chemo- and stereoselectivity and gives access to several members of the loline alkaloid family. It delivers sufficient material to support a programme aimed at studying the complex interactions between plants, fungi, insects and bacteria brokered by loline alkaloids.
Asymmetric synthesis of (+)-loline, a pyrrolizidine alkaloid from rye grass and tall fescue
Blakemore,Kim,Schulze,White,Yokochi
, p. 1831 - 1845 (2007/10/03)
(+)-Loline (1) was synthesized via a pathway that employed intramolecular [4 + 2] cycloaddition of an acylnitrosodiene, 25 or 26, as a key step. The acylnitrosodienes, which were used in situ, were obtained by oxidation of the corresponding hydroxamic acids, 17 and 24, and these were prepared from either glucose via aldehyde 9 or more directly from (S)-malic acid (18). The endo dihydrooxazines 27 and 29, obtained in a mixture with their exo stereoisomer, were transformed by reductive N-O bond cleavage and reannulation into pyrrolizines 34 and 35. The latter was subjected to Sharpless aminohydroxylation in the presence of (DHQD)2PHAL to give 50 along with its regioisomer 51. N-Methylation of tosyl amide 50, followed by mesylation of alcohol 52 and reduction of the γ-lactam 53 with borane, afforded pyrrolizidine 54. Cleavage of the p-methoxybenzyl ether and subsequent thermal treatment of 55 resulted in intramolecular etherification to yield N-tosylloline (57). Final reductive cleavage of the N-tosyl residue produced (+)-loline, characterized as its dihydrochloride.
Asymmetric synthesis of (+)-loline
Blakemore, Paul R.,Schulze, Volker K.,White, James D.
, p. 1263 - 1264 (2007/10/03)
The first asymmetric synthesis of (+)-loline has been achieved in 20 steps from (-)-malic acid by a route incorporating intramolecular hetero- Diels-Alder cycloaddition of an acylnitrosodiene.
Synthesis of the Lolium Alkaloids
Tufariello, Joseph J.,Meckler, Harold,Winzenberg, Kevin
, p. 3556 - 3557 (2007/10/02)
The total synthesis of loline and norloline using a nitrone-based methodology is reported herein.
