The reaction between palladium acetate and IMES·HCl leads to the formation of a novel complex. X-ray crystal structure analysis reveals that is C(2) bound one NHC ligand (the normal binding mode), whereas second attached through C(5) carbon imidazolium. metalation site on imidazolium salt strongly influenced by presence base. Furthermore, mode Pd shown substantially affect catalytic behavior complexes in cross-coupling reactions.

The possibility of finding novel disconnections for the efficient synthesis organic molecules has driven interest in developing technologies to directly functionalize C–H bonds. ubiquity these bonds makes such transformations attractive, while also posing several challenges. first, and perhaps most important, is selective functionalization one bond over another. Another key problem inducing reactivity at sites that have been historically unreactive difficult access without prior inefficient...

This communication describes a metal-free methodology involving an efficient and controlled reduction of secondary amides to imines, aldehydes, amines in good excellent yields under ambient pressure temperature. The process includes chemoselective activation amide with triflic anhydride the presence 2-fluoropyridine. electrophilic activated can then be reduced corresponding iminium using triethylsilane, cheap, rather inert, commercially available reagent. Imines isolated after basic workup...

We have developed an efficient catalytic enantioselective hydrogenation of pyridine derivatives. Enhanced reactivity was possible by optimization the electronic properties catalyst through ligand modification. This methodology shows particular N-iminopyridinium ylides that provides access to substituted piperidines in good enantiomeric excesses.

This communication describes the chemoselective metal-free reduction of tertiary amides to corresponding amines. Hantzsch ester is used as a mild reducing agent for trifluoromethanesulfonic anhydride activated providing amines with high functional group tolerance.

The total synthesis of the marine macrolide bryostatin 2 is described. plan relies on aldol and directed reduction steps in order to construct anti-1,3-diol array present each principal subunits (A, B, C). These fragments were coupled using a Julia olefination subsequent sulfone alkylation. A series functionalization reactions provided bryopyran seco acid, which was macrolactonized under Yamaguchi conditions. Installation two enoate moieties took advantage asymmetric phosphonate condensation...

Useful empirical insights onto the enantioinduction process of chiral Rh(II)-carboxylate catalysts are described in first catalytic asymmetric cyclopropanation alkenes with α-nitro diazoacetophenones. X-ray, solution NMR, and reactivity studies made on these complexes suggest that level induction strongly depends their active symmetry, which turn relies nature ligands' substituents. The catalyst's 'All Up' reactive conformation resulted being necessary to obtain good stereoselectivity,...

A very effective chiral controller has been found for the conversion of allylic alcohols into corresponding enantiomerically enriched cyclopropanes using bis(iodomethyl)zinc. variety chiral, nonracemic cyclopropylmethanols could be obtained according to this method. This methodology was extended with success cyclopropanation unconjugated and conjugated polyenes homoallylic alcohols. The carbamates also investigated system, but it that enantioenriched cyclopropylmethylamines are best prepared...

The cycloaddition of aromatic azomethine imines to 1,1-cyclopropane diesters was achieved using Ni(ClO4)2 as catalyst. methodology gives access unique tricyclic dihydroquinoline derivatives with dr up 6.6:1. A nonconcerted mechanism is proposed on the basis stereochemical analysis reaction.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDesign of Amphoteric Bifunctional Ligands: Application to the Enantioselective Simmons-Smith Cyclopropanation Allylic AlcoholsAndre B. Charette and Helene JuteauCite this: J. Am. Chem. Soc. 1994, 116, 6, 2651–2652Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://pubs.acs.org/doi/10.1021/ja00085a068https://doi.org/10.1021/ja00085a068research-articleACS PublicationsRequest reuse...

[reaction: see text] 1-Nitro- and 1-cyano-cyclopropyl ketones have been prepared in an expedient manner from cyclopropanation reactions of alkenes by diazo compounds or situ-generated phenyliodonium ylides catalyzed Rh(II) carboxylates. The doubly activated cyclopropanes were used as synthetic precursors for the regiospecific synthesis 4-nitro- 4-cyano-dihydropyrroles upon treatment with primary amines. Oxidation dihydropyrroles DDQ allows rapid access to densely functionalized pyrroles.

A general and efficient iron-catalyzed direct arylation of benzene hetereoaryl derivatives using a cost-effective environmentally benign catalyst is described. The reaction performed under neat conditions can proceed at room temperature.

Palladium-catalyzed direct C−H arylation of N-iminopyridinium ylides provides a powerful and versatile method for the synthesis functionalized piperidines in good yields. Chemoselective functionalization pyridinium ring presence pyridine substituent is possible as exemplified by expedient anabasine 61% overall yield over three steps.

Potassium tert-butoxide mediated intramolecular cyclization of aryl ethers, amines, and amides was efficiently performed under microwave irradiation to provide the corresponding products in high regioisomeric ratios. The reaction proceeds via single-electron transfer initiate formation an radical, followed by a kinetically favored 5-exo-trig subsequent ring expansion.

A highly enantioselective (up to 97.5% ee) and diastereoselective (95:5 dr trans/cis) Cu(I)-catalyzed cyclopropanation of alkenes using phenyliodonium ylide generated in situ from iodosobenzene methyl nitroacetate is reported. The took place with high enantioselectivity for a wide range alkenes, the reaction was performed at room temperature. 1-Nitrocyclopropyl esters are versatile building blocks access corresponding cyclopropane amino aminocyclopropanes two three steps, respectively,...

The Lewis acid-catalyzed ring-opening of methyl 1-nitrocyclopropanecarboxylates with amine nucleophiles is described. reaction proceeds at room temperature and complete preservation the enantiomeric purity from electrophilic center cyclopropane to acyclic product. methodology was applied in an enantioselective synthesis dual serotonin/norepinephrine reuptake inhibitor (3R)-3-(1H-indol-1-yl)-N-methyl-3-phenylpropan-1-amine.

Different diacceptor diazo compounds bearing an α-PMP-ketone group were found to be effective carbene precursors for the highly stereoselective Rh(2)(S-TCPTTL)(4)-catalyzed cyclopropanation of alkenes (EWG = NO(2), CN, CO(2)Me). The resulting products readily transformed into a variety biologically relevant enantiopure molecules, such as cyclopropane α- and β-amino acid derivatives. mechanistic studies carried out led rationale high diastereo- enantioselectivity obtained, where PMP-ketone...

Synthesis of chiral sulfones: A copper–phosphine complex efficiently provided optically active alkyl phenyl sulfones by hydrosilylation at room temperature. The reduction β,β-disubstituted vinyl in the presence Me-DuPhos monoxide ligand lead to excellent enantiomeric excesses and high yields (see scheme). prepared were desulfonylated subjected Julia olefination conditions.

A versatile Cu-catalyzed direct CH alkenylation of N-iminopyridinium ylides, compatible with several different copper sources (including a penny), provides powerful and inexpensive method for the synthesis functionalized pyridine derivatives. Chemoselective functionalization halide-containing compounds allows alkenyl pyridines containing reactive tethers further functionalization. Detailed facts importance to specialist readers are published as ”Supporting Information”. Such documents...

A mild and highly stereoselective rhodium(II)-catalyzed cyclopropanation of alkenes, alkynes, allenes with diacceptor diazo compounds is reported. Using the phosphonate moiety as an efficient trans-directing group, first catalytic asymmetric route to cycloprop(en)ylphosphonates was developed by employing α-cyano diazophosphonate Rh(2)(S-IBAZ)(4) chiral catalyst. The isosteric character phosphonic carboxylic acid derivatives allowed alternative use ester in process, leading...

A borocyclopropanation of (E)- and (Z)-allylic ethers styrene derivatives via the Simmons-Smith reaction using a novel boromethylzinc carbenoid is described. The precursor prepared 3-step sequence from inexpensive commercially available starting materials. This methodology allows for preparation 1,2,3-substituted borocyclopropanes in high yields diastereoselectivities. Several postfunctionalization reactions were also performed to illustrate versatility these building blocks.