Phenol-directed enantioselective allylation of aldimines and ketimines

[Structure: see text] Phenols are effective directing and activating groups for our allylchlorosilane reagents, allowing the highly enantioselective allylation of a range of 2-aminophenol-derived aldimines. When the phenol is incorporated into the substrate ketimines may be allylated highly enantioselectively, leading to the experimentally simple synthesis of a range of tertiary carbinamine structures.     

Stereoselective Barbier-type allylation reaction of trifluoromethyl aldimines

Trifluoromethyl aldimines could react, under Barbier conditions in the presence of activated zinc, in DMF at room temperature or in THF at reflux, with various allyl bromides to provide the corresponding homoallylamines. Secondary homoallyl trifluoromethylamines were stereoselectively obtained from the optically active aldimine 12 with an excellent diastereoisomeric excess (98%).     

Enantioselective hydrocyanation of N-protected aldimines

Enantioselective hydrocyanation of N-benzyloxycarbonyl aldimines catalyzed by a Ru[(S)-phgly](2)[(S)-binap]/C(6)H(5)OLi system or a bimetallic complex [Li{Ru[(S)-phgly](2)[(S)-binap]}]Cl affords the amino nitriles in 92-99% ee. The reaction is carried out in tert-C(4)H(9)OCH(3) with a substrate-to-catalyst molar ratio in the range of 500-5000 at -20 to 0 °C. Primary, secondary, and tertiary alkyl imines as well as the aryl and heteroaryl substrates are smoothly cyanated to produce the desired products in high yield.     

A general method for the preparation of N-sulfonyl aldimines and ketimines

[Reaction: see text] A simple procedure to obtain N-sulfonyl imines involving the condensation of carbonyl compounds with p-tolyl or tert-butyl sulfinamides followed by oxidation with m-CPBA of the resulting N-sulfinylimines is reported. The method is applicable to aldehydes (aliphatics and aromatics) and ketones (diaryl, dialkyl, and aryl alkyl), even those containing enolizable protons. It also does not affect C=N or C=C double bonds and does not epimerize alpha-stereogenic centers.     

Reverse-docking study of the organocatalyzed asymmetric Strecker hydrocyanation of aldimines and ketimines

A methodology for reverse-docking flexible organocatalysts to rigid transition state models of catalyst-free asymmetric reactions has been developed. The investigation of Jacobsen's chiral thiourea-based organocatalyst for the hydrocyanation of aldimines and ketimines (Strecker reaction) via reverse-docking is described. Results from reverse-docking Jacobsen's organocatalyst to both enantiomers of six Strecker TS-models (i.e., rigid transition state models of the catalyst-free asymmetric reaction) indicate a clear energetic preference for binding the organocatalyst to the R-enantiomer TS-model, which is in agreement with experimental results. The most favorable docking poses reveal structural features consistent with principles of molecular recognition, catalysis, and NMR data. These poses may represent simplified geometric models of the transition state for the catalyzed reaction.     

First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

A new organocatalytic system, novel chiral bisformamide and in situ generated L-proline-derived allylsilane reagent , which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.     

Solvent-free allylation and benzylation of aldimines mediated by zinc powder

A rapid and efficient procedure for allylation and benzylation of aldimines mediated by zinc powder under solvent-free conditions is described. The procedure is operationally simple, higher regioselective, and gives good to excellent yields.     

Metal-free catalytic reduction of aldehydes,ketones,aldimines,and ketimines

<正>The metal-free combination of catalytic amounts of PPh_3,B(C_6F_5)_3,and PhSiH_3 can efficiently hydrosilylate aldehydes, ketones,aldimines and ketimines to afford the corresponding reduction products in good yields.     

Asymmetric synthesis of protected 1,2-amino alcohols using tert-butanesulfinyl aldimines and ketimines.

tert-Butanesulfinyl aldimines and ketimines bearing an alpha-benzyloxy or alpha-silyloxy substituent serve as precursors in the synthesis of protected 1,2-amino alcohols in high yields and diastereoselectivities. General protocols are described for the addition of unbranched alkyl, branched alkyl, and aryl organometallic reagents to N-sulfinyl aldimines 1 and 2 and ketimines 5 and 6. Furthermore, the selective N- or O-deprotection of sulfinamide products 3, 4, 7, and 8 is described, enabling further synthetic transformations of the reaction products.     

Enantioselective conjugate allylation of cyclic enones

Enantioselective organocatalytic 1,2-allylation of a cyclic enone followed by anionic oxy-Cope rearrangement delivered the ketone as a mixture of diastereomers. This appears to be a general method for the net enantioselective conjugate allylation of cyclic enones.     

A convenient and practical method for the synthesis of N‐thiophosphoryl aldimines and ketimines

A convenient and practical method for the preparation of N‐thiophosphoryl imines was developed through the thermal condensation of acetals with different thiophosphoramides at 120–160°C. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:238–244, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20412     

Enantioselective allylation of aldehydes with chiral allyl organolanthanide reagents

The first example of enantioselective allylation of aldehydes with chiral allyl organolan-thanide reagents has been achieved in high chemical yield and moderate optical purity (up to 54% e.e.).     

Highly efficient three-component synthesis of protected homoallylic amines by bismuth triflate-catalyzed allylation of aldimines

Bismuth triflate catalyzes the allylation of a variety of in situ generated protected aldimines using aldehydes, primary carbamates, and allyltrimethylsilane in a three-component reaction. The reaction proceeds rapidly and affords the corresponding protected homoallylic amine in good yield (up to 86%). Scope and limitations of the aldehyde and carbamate components are reported.     

Enantioselective hydrosilylation of ketimines with trichlorosilane promoted by chiral N-picolinoylaminoalcohols

Enantioselective hydrosilylation of N-aryl and N-benzyl ketimines with trichlorosilane catalyzed by readily accessible chiral N-picolinoylaminoalcohols proceeded smoothly furnishing chiral secondary amines in good yields (up to 93%) and moderate to excellent enantioselectivities (up to 95% ee).     

Enantioselective allylation of aldehydes promoted by chiral sulfur reagents

The addition of allylzinc bromide to aldehydes was studied with different chiral sulfur compounds acting as a catalyst. Yield differences and enantiomeric excesses were observed.     

Enantioselective radical allylation reactions using chiral lanthanide Lewis acids

Radical additions to oxazolidinone acrylate followed by allyl trapping were studied with chiral Lewis acids derived from lanthanide salts. Chiral ligands were evaluated to establish the -stereocenter. Ligands with a prolinol framework along with achiral additives proved to be effective. The observed trends are compared with those in the literature.     

Tetrameric zirconium(IV) compounds derived from oxozirconium(IV) chloride and heterocyclic aldimines and ketimines

Summary Interaction of ZrOCl₂:8H₂O, [Zr₄(OH)₈(H₂O)₁₆]Cl₈ 12H₂O, with the heterocyclic, aldimines (PyAlA) and heterocyclic ketimines (AcPyA) in Me₂CO in the presence of HC(OEt)₃ yields white amorphous compounds of the type [Zr₄(OH)₁₂(H₂O)₈(PyAlA)₂]Cl₄ and [Zr₄(OH)₁₂(H₂O)₁₀(AcPyA)]Cl₄. Presumably these compounds have a tetrameric dodecahedral structure, derived from the parent. The analytical data, i.r., electrical conductance and t.g. measurements all favour the tetrameric formulation. The t.g. studies also indicate the intermediacy of complex species, which lose water and the Schiff base ligands, with increase in temperature.     

Enantioselective organocatalytic substitution of alpha-cyanoacetates on imidoyl chlorides--synthesis of optically active ketimines

The enantioselective substitution of alpha-cyanoacetates on imidoyl chlorides under phase-transfer catalytic conditions is presented; a simple quinidine-derived phase-transfer catalyst gives access to the products, highly substituted ketimines, in generally good yields and up to 90% ee.     

P′CP′-Pincer palladium complex-catalyzed allylation of N,N-dimethylsulfamoyl-protected aldimines

The P′CP′-pincer palladium complex-catalyzed allylation of N,N-dimethylsulfamoyl-protected aldimines with allyl(tributyl)stannane is investigated for the preparation of N-homoallylic sulfamides. The desired N,N-dimethylsulfamoyl-protected products are obtained in moderate to high yields in DMF under very mild conditions and a high yielding and convenient deprotection of the N,N-dimethylsulfamoyl group is also demonstrated.