A palladium-catalyzed aminoalkynylation strategy towards bicyclic heterocycles: Synthesis of (±)-trachelanthamidine
Sweet cyclizations: The synthesis of pyrrolizidines and indolizidines has been achieved. Olefins were subjected to an intramolecular palladium-catalyzed aminoalkynylation with the hypervalent iodine reagent TIPS-EBX. After removal of the protecting group, a two-step cyclization sequence and subsequent reduction led to the natural product (±)-trachelanthamidine (see scheme; TIPS-EBX=triisopropylsilyl ethynylbenziodoxolone).
Nicolai, Stefano,Piemontesi, Cyril,Waser, Jerome
supporting information; experimental part
p. 4680 - 4683
(2011/06/23)
Ring-closing olefin metathesis for the synthesis of fused nitrogen heterocycles
A novel technique for the efficient synthesis of fused nitrogen heterocycles containing various combinations of five- and eight-membered rings has been developed. This method features the ring-closing metathesis (RCM), which is catalyzed by the molybdenum
Martin, Stephen F.,Chen, Hui-Ju,Courtney, Anne K.,Liao, Yusheng,Paetzel, Michael,Ramser, Melissa N.,Wagman, Allan S.
p. 7251 - 7264
(2007/10/03)
Reaction of Novel Imide Reducing Reagents with Pyrrolizidinediones
The reduction of pyrrolizidinediones 4a and 4b with (i-Bu)2AlH and LiBHEt3 affords the corresponding hexahydro-5-hydroxy-3H-pyrrolizin-3-ones 8a and 8b in good yield.LiBHEt3 also reduces N-methylglutarimide (18) in 53percent yield.The combination of NaBH4/MeOH/Ac2O/CH2Cl2 selectivity reduces an imide in the presence of an ester.Hexahydro-5-(methylthio)-3H-pyrrolizin-3-ones are products of the NaBH4 reduction of pyrrolizidinediones in MeSH/CH2Cl2/Ac2O.The reduction products, thioethers (5a-c) and lactamols (8a-c), are intermediates in the synthesis of pyrrolizinones 1a-c.
Thomas, Edward W.,Rynbrandt, Ronald H.,Zimmermann, David C.,Bell, Larry T.,Muchmore, Christine R.,Yankee, Ernest W.
p. 4535 - 4543
(2007/10/02)
Pyrrolizidine-3-ones
The present invention provides certain 2,3-didehydro-5-oxopyrrolizidinones and indolizidinones which are useful as lipid-altering and anti-atherosclerotic agents.
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(2008/06/13)
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