92011-93-3Relevant academic research and scientific papers
Pd-catalyzed asymmetric allylic amination with BOP ligands and its applications to the synthesis of fused polycyclic alkaloids
Zang, Yang,Ojima, Iwao
supporting information, p. 3288 - 3292 (2015/05/27)
Abstract Pd-catalyzed asymmetric allylic amination reaction of piperonylamides and a 2-siloxymethylcyclohexenyl carbonate, using chiral biphenol-based diphosphinite (BOP) ligands gave the corresponding cyclohexenylpiperonylamides in excellent yield and en
Pd-catalyzed asymmetric allylic etherification using chiral biphenol-based diphosphinite ligands and its application for the formal total synthesis of (-)-galanthamine
Zang, Yang,Ojima, Iwao
, p. 4013 - 4018 (2013/07/05)
A library of novel chiral biphenol-based diphosphinite (BOP) ligands was designed and created. These BOP ligands were applied to a Pd-catalyzed intermolecular allylic etherification reaction, which provided a key intermediate for the formal total synthesis of (-)-galanthamine with 97% ee in 97% yield.
Synthesis of chiral biphenol-based diphosphonite ligands and their application in palladium-catalyzed intermolecular asymmetric allylic amination reactions
Shi, Ce,Chien, Chih-Wei,Ojima, Iwao
, p. 674 - 680 (2011/10/12)
A library of new 2,2'-bis(diphenylphosphinoyloxy)-1,1'-binaphthyl (binapo)-type chiral diphosphonite ligands was designed and synthesized based on chiral 3,3',5,5',6,6'-hexasubstituted biphenols. These bop ligands have exhibited excellent efficiency in a palladium-catalyzed intermolecular allylic amination reaction, which provides a key intermediate for the total synthesis of Strychnos indole alkaloids with enantiopurities of up to 96% ee. A library of chiral diphosphonite (bop) ligands was synthesized based on chiral hexasubstituted biphenols with fine-tuning capability. Their application for the synthesis of a key intermediate to indole alkaloids through a palladium-catalyzed intermolecular asymmetric allylic amination is reported (TBS=tert-butyldimethylsilyl, TIPS=triisopropylsilyl, dba=dibenzylideneacetone). Copyright
Synthesis of 2-substituted cyclohexene derivatives through cross-coupling reactions via π-allylmetal intermediate using N-heterocyclic carbenes (NHCs) as ligands
Yamazaki, Tetsuro,Sato, Yoshihiro
experimental part, p. 2830 - 2834 (2009/04/04)
Palladium- or nickel-catalyzed cross-coupling reactions of 2-substituted cyclohexenes, which are generally less reactive than those having no substituent at the C2 position, with organotin reagents (Migita-Kosugi-Stille coupling) or with Grigard reagents (Kumada-Tamao-Corriu coupling) using a NHC as a ligand was investigated. It was found that NHCs are effective as ligands for these reactions, giving the corresponding cross-coupling products in good yields. Georg Thieme Verlag Stuttgart.
Divergent enantioselective synthesis of (-)-galanthamine and (-)-morphine
Trost, Barry M.,Tang, Weiping,Toste, F. Dean
, p. 14785 - 14803 (2007/10/03)
An efficient divergent synthetic strategy for the synthesis of the opiate and amaryllidaceae alkaloids emerges by employing a Pd-catalyzed asymmetric allylic alkylation (AAA) to set the stereochemistry. Three generations of syntheses of galanthamine are discussed in detail with particular focus on the scope of the palladium-catalyzed AAA reactions and intramolecular Heck reactions. The pivotal tricyclic intermediate is available in six steps from 2-bromovanillin and the monoester of methyl 6-hydroxycyclohexene-1-carboxylate. This intermediate requires only two steps to convert to (-)-galanthamine. Using a Heck vinylation, we found that the fourth ring of codeine/morphine could be formed. The final ring formation involves a novel visible light-promoted hydroamination. Thus, six steps are required to convert the pivotal tricyclic intermediate into codeine, which has been demethylated in high yield to morphine.
Regioselectivity of the Intermolecular Diels-Alder Reaction of Acyl Nitroso Compounds (C-Nitrosocarbonyl Compounds) and Nitrosoformates (O-Nitrosocarbonyl Compounds). Preparation of Functionalized cis-Δ6-1-Octalones
Boger, Dale L.,Patel, Mona,Takusagawa, Fusao
, p. 1911 - 1916 (2007/10/02)
A study of the regioselectivity of the intermolecular Diels-Alder reaction of (nitrosocarbonyl)benzene and methyl nitrosoformate with representative electron-rich and electron-deficient 2-substituted 1,3-cyclohexadienes is described.The observed results are consistent with the prediction that nitrosocarbonyl compounds behave as dependable electron-deficient 2? components in a normal (HOMOdiene controlled) Diels-Alder reaction with electron-rich 2-substituted dienes and additionally illustrate that they may serve as useful 2? components in regioselective Diels-Alder reactions with electron-deficient 2-substituted 1,3-cyclohexadienes.The latter results are consistent with either a normal (HOMOdiene controlled) or inverse electron demand (LUMOdiene controlled) Diels-Alder reaction.Utilization of the nitrosocarbonyl Diels-Alder adducts in a stereospecific preparation of functionalized, cis-Δ6-1-octalone is detailed.In contrast to predictions based on secondary orbital control (allylic axial heteroatom orbital control), cycloaddition of butadiene with the 5- and 6-substituted N-benzoyl 3-aza-2-oxobicyclooct-5-enes occurs on the face bearing the RCON-O bridge.
