An asymmetric approach to the pyrrolizidine ring system via N-acetyl and N-propionyl anion cyclisation processes
An efficient route to the pyrrolizidine ring system has been developed. The method, which uses N-acetyl and N-propionyl anion cyclisation reactions as the key steps has provided the natural pyrrolizidines (-)-(1R, 8S)-1-hydroxypyrrolizidine (10), (-)-pyrrolizidin-1-ene-3-one (13), (±)-trachelanthamidine (18) together with a range of 2-methyl substituted pyrrolizidine-3-ones.
Murray,Murray, Anthony,Proctor,Proctor, George R.,Murray,Murray, P. John
Enantioselective sp3 C-H alkylation of γ-butyrolactam by a chiral Ir(i) catalyst for the synthesis of 4-substituted γ-amino acids
Ir-catalyzed sp3 C-H alkylation of γ-butyrolactam with alkenes was used for the highly enantioselective synthesis of 5-substituted γ-lactams, which were readily converted into chiral 4-substituted γ-amino acids. A broad scope of alkenes was amenable as coupling partners, and the alkylated product using acrylate could be transformed into the key intermediate of pyrrolam A synthesis.
Intramolecular Wittig reaction: A new synthesis of (S)-pyrrolam A
A straightforward synthesis of (S)-pyrrolam A is described. The synthesis involves in situ generation of the phosphorane 3, followed by an intramolecular Wittig reaction to furnish (S)-pyrrolam A.
Majik, Mahesh S.,Parameswaran, Perunninakulath S.,Tilve, Santosh G.
experimental part
p. 1500 - 1504
(2009/02/07)
A short synthesis of (S)-pyrrolam a via domino oxidation-Wittig reaction
A short synthesis of (S)-pyrrolam A starting from readily available N-(benzyloxycarbonyl)-L-prolinol is described that makes use of a domino primary alcohol oxidation-Wittig reaction as the key step. Georg Thieme Verlag Stuttgart.
Short syntheses of (-)-(R)-Pyrrolam A and (1S)-1-hydroxyindolizidin-3-one
(-)-(R)-Pyrrolam A was prepared in five steps, 95% ee and 25% yield, from (R)-benzyl prolinate. Closure of the pyrrolidine ring was effected by a domino addition-Wittig alkenation reaction with ylide Ph3PCCO, immobilized on a polystyrene resin.
Schobert, Rainer,Wicklein, Andre
p. 1499 - 1502
(2008/02/08)
Construction of chiral 1,2-cycloalkanopyrrolidines from L-proline using ring closing metathesis (RCM)
An efficient synthetic method for the preparation of optically active pyrroloazocine, pyrroloazepine, quinolizidine, indolizidine using ring closing olefin metathesis (RCM) is described.
An efficient route to the pyrrolizidine ring system via an N-acyl anion cyclisation process
An enantioselective route to the pyrrolizidine ring system has been developed which uses an N-acyl anion cyclisation reaction as the key step. This methodology has provided the natural pyrrolizidines (-)-(1R, 8S)-1-hydroxy-pyrrolizidine 7, (-)-pyrrolizidin-1-ene-3-one 9 and (±)-trachelanthamidine 14. Extension of the process to an N-propionyl substrate provides ready access to a series of 2-methyl pyrrolizidines.
Murray, Anthony,Proctor, George R.,Murray, P. John
p. 3757 - 3766
(2007/10/03)
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