70494-70-1Relevant articles and documents
Asymmetric syntheses of the 1-hydroxymethyl-2-hydroxy substituted pyrrolizidines (?)-macronecine, (?)-petasinecine, (?)-1-epi-macronecine, (+)-1-epi-petasinecine and (+)-2-epi-rosmarinecine
Brambilla, Marta,Davies, Stephen G.,Fletcher, Ai M.,Roberts, Paul M.,Thomson, James E.
, p. 7449 - 7461 (2016)
The asymmetric syntheses of all four possible diastereoisomeric 1-hydroxymethyl-2-hydroxy substituted pyrrolizidines, (?)-macronecine, (?)-petasinecine, (?)-1-epi-macronecine and (+)-1-epi-petasinecine, are reported. Conjugate addition of lithium (S)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl (E)-hepta-2,6-dienoate, followed by aldol reaction with acrolein under various conditions gave four possible diastereoisomeric β-amino esters with the required stereogenic centres installed. In each case, the pyrrolizidine scaffold was rapidly accessed by reduction of the ester moiety followed by a sequential two-step protocol involving ozonolysis and hydrogenolysis/double reductive cyclisation. Following this route, (?)-macronecine, (?)-petasinecine, (?)-1-epi-macronecine and (+)-1-epi-petasinecine were synthesised in 21, 14, 10 and 19% overall yield, respectively, in six steps or fewer from commercially available starting materials. An analogous strategy employing enantiopure tert-butyl (R,E)-4-(triethylsilyloxy)hepta-2,6-dienoate facilitated the asymmetric synthesis of (+)-2-epi-rosmarinecine in 21% overall yield and >99:1 dr, in 13 steps from commercially available starting materials.
Cascade oxime formation, cyclization to a nitrone, and intermolecular dipolar cycloaddition
Furnival, Rachel C.,Saruengkhanphasit, Rungroj,Holberry, Heather E.,Shewring, Jonathan R.,Guerrand, Hélène D. S.,Adams, Harry,Coldham, Iain
, p. 10953 - 10962 (2016/12/06)
Simple haloaldehydes, including enolisable aldehydes, were found to be suitable for the formation of cyclic products by cascade (domino) condensation, cyclisation, dipolar cycloaddition chemistry. This multi-component reaction approach to heterocyclic compounds was explored by using hydroxylamine, a selection of aldehydes, and a selection of activated dipolarophiles. Initial condensation gives intermediate oximes that undergo cyclisation with displacement of halide to give intermediate nitrones; these nitrones undergo in situ intermolecular dipolar cycloaddition reactions to give isoxazolidines. The cycloadducts from using dimethyl fumarate were treated with zinc/acetic acid to give lactam products and this provides an easy way to prepare pyrrolizinones, indolizinones, and pyrrolo[2,1-a]isoquinolinones. The chemistry is illustrated with a very short synthesis of the pyrrolizidine alkaloid macronecine and a formal synthesis of petasinecine.
Extremely high regio- and stereoselective C-C bond formation of substituted γ-hydroxylactams: synthesis of macronecines based on their structural duality
Sengoku, Tetsuya,Suzuki, Takamasa,Kakimoto, Tatsuro,Takahashi, Masaki,Yoda, Hidemi
experimental part, p. 2415 - 2423 (2009/07/18)
With a view to develop a new synthetic entry for the necine bases, treatment of functionalized γ-hydroxylactams was found to undergo quite high regio- and diastereoselective carbon-carbon bond formation reactions, affording the corresponding structurally
Synthesis of the necine bases (±)-macronecine and (±)-supinidine via an aza-ene reaction and allylsilane induced ring closure
Sarkar, Tarun K.,Hazra, Anindya,Gangopadhyay, Pulak,Panda, Niranjan,Slanina, Zdenek,Lin, Chun-Cheng,Chen, Hui-Ting
, p. 1155 - 1165 (2007/10/03)
An aza-ene reaction has been used for the first time for the synthesis of two 5-membered lactam-hydrazides, each with a built-in allylsilane terminator for further elaboration. One of the lactam-hydrazides was transformed via an allylsilane-hydrazonium io
β-Amino ester route to tussilagine, isotussilagine and (-)-petasinecine
Ma, Dawei,Zhang, Jianhua
, p. 1703 - 1707 (2007/10/03)
Condensation of enantiopure β-amino ester 2a with methyl pyruvate provides two diastereoisomers 3 and 4. Both 3 and 4 are subjected to hydrogenation followed by cyclization producing pyrrolidinones 5 and 8. From 5 and 8 isotussilagine and tussilagine are obtained respectively, by using a Mitsunobu reaction as a key step. In a similar manner, (-)-petasinecine is synthesized from the condensation product of 2b with ethyl glyoxalate.
Highly Diastereoselective Synthesis of (-)-Petasinecine via Ireland-Claisen-Type Rearrangement
Mulzer, Johann,Shanyoor, Mazin
, p. 6545 - 6548 (2007/10/02)
A Highly diastereoselective synthesis of petasinecine from L-proline via an Ireland-Claisen-type rearrangement (5->7; Scheme 1) is described.Keywords: necine base, petasinecine, L-proline, Ireland-Claisen-type rearrangement
THE SYNTHESIS OF (1R,2S,8S)- AND (1S,2S,8S)-1-HYDROXYMETHYL-2-HYDROXYPYRROLIZIDINE: PETASINECINE AND ITS C-1 EPIMER
Rueeger, Heinrich,Benn, Michael
, p. 235 - 237 (2007/10/02)
The hydrogenation of (8S)-1-ethoxycarbonylpyrrolizidin-2-one in aqueous acetic acid, over Adam's catalyst, afforded a separable mixture of (1R,2S,8S)- and (1S,2S,8S)-1-ethoxycarbonylpyrrolizidin-2-ol.Reduction of the individual epimers with lithium aluminium hydride gave the corresponding diols, the (1R,2S,8S)-compound being petasinecine.
