Platinum-catalyzed allylation of aminonaphthalenes with allylic acetates in water

The activation of C-O bonds in allylic acetates in water as a suspension medium has been accelerated by carrying out the reactions in the presence of platinum complexes associated with ligands. The platinum-catalyzed allylation of aminonaphthalenes using allylic acetates gave the corresponding N-allylic aminonaphthalenes in good yields.     

Simple palladium‐catalyzed C–N bond formation for poor nucleophilicity of aminonaphthalenes

Aromatic amines is not used commonly in allylic amination, presumably because of their less nucleophilic nature compared with the more extensively used benzylamine or relatively stable anionic nitrogen nucleophiles. An eco‐friendly method for C–O bond activation of allylic acetates using palladium associated with ligands in water leading to N‐allylation was described in this study. The palladium‐catalyzed allylic amination of allylic acetate with aminonaphthalenes gave 34–95% yields to the corresponding N‐allylic aminonaphthalenes. Copyright © 2011 John Wiley & Sons, Ltd.     

PEG‐4000‐promoted palladium‐catalyzed N‐allylation in water: aminonaphthalene as an example

An environmentally friendly, efficient catalytic process using palladium associated with ligands in a PEG4000–water system leading to N‐allylation was described in this study. PEG‐4000 was found to improve the palladium‐catalyzed allylic amination of allylic acetates with aminonaphthalenes and gave overall good to high yields of the corresponding N‐allylic aminonaphthalenes. Copyright © 2012 John Wiley & Sons, Ltd.     

Direct palladium(0)-catalyzed amination of allylic alcohols with aminonaphthalenes

The direct activation of CO bonds in allylic alcohols by palladium complexes has been accelerated by carrying out the reactions in the presence of titanium reagents. The palladium-catalyzed amination of allylic alcohols using aminonaphthalenes gave N-allylic naphthylamines in good yields. The monoallylation products are formed in the main.     

Copper triflate/t-BuOOAc-catalyzed amidation of allylic and benzylic acetates with sulfonamides

A copper triflate/t-BuOOAc-catalyzed amidation of allylic and benzylic acetates has been developed which is suitable for the coupling of a wide variety of functionalized sulfonamide nucleophiles with acetate electrophiles. The methodology allows for the amidation of benzylic substrates which are not further activated by an additional adjacent alkene or alkyne, enabling simple allylic acetates and primary benzylic acetates to be used as reaction partners.     

Palladium-catalyzed and samarium-promoted coupling of stereochemically-biased allylic acetates with carbonyl compounds

Stereochemically-biased bicyclic allylic acetates endo- and exo-1 were shown as being allyl donors for Pd-catalyzed carbonyl allylation using stoichiometric quantities of samarium diodide. Cyclopentenyl acetate and bicyclic derivatives 1 react with cyclic ketones in the presence of SmI₂ without requirement of palladium catalysis. Use of enantiomerically enriched substrate suggests that the reaction goes through a π-allyl samarium complex. However, this reactivity appears to be restricted to strained cyclopentenyl acetates since other linear and cyclic allylic acetates do not give the carbonyl allylation product.     

Preparation of N-protected allylic amines and α-methylene-β-amino acids from vinylalumination/Baylis-Hillman products via tandem SN2′ substitution-Overman rearrangement

S_N2′ reaction on the acetates obtained from vinylalumination or Baylis-Hillman products, followed by in situ reduction afforded allylic alcohols. Upon conversion to trichloroacetimidates and [3,3]-sigmatropic rearrangement, the corresponding N-protected β-substituted allylic amines were obtained in good yields. Utilization of hydroxy group as the nucleophile furnished allylic hydroxy esters, which were converted to protected α-methylene-β-amino acids via Overman rearrangement.     

Synthesis of fluorinated glutamic acid derivatives via vinylalumination

A variety of structural types of fluorinated allylic acetates, prepared by vinylalumination of fluorinated aldehydes, were reacted with the benzophenone imine of glycine tert-butyl ester to provide 4-(fluorobenzylidenyl)- and 4-(fluoroalkylidenyl) glutamic acid derivatives in 61-96% yield. The 4-(4-fluorobenzylidenyl) glutamic acid derivative was hydrolyzed to give the 4-(4-fluorobenzylidenyl)pyroglutamate and then hydrogenated to the 4-(4-fluorobenzyl)pyroglutamate. The catalytic enantioselective conjugate addition-elimination of the benzophenone imine of glycine tert-butyl ester with the fluorinated allylic acetates prepared from fluoral, pentafluorobenzaldehyde, and 2,6-difluorobenzaldehyde provided the corresponding 4-(fluoroalkylidenyl)- and 4-(fluorobenzylidenyl) glutamic acid derivatives in 42, 45 and 80% ee, respectively.     

Arylations of allylic acetates with triarylbismuths as atom-efficient multi-coupling reagents under palladium catalysis

Arylation of allylic acetates employing triarylbismuths as multi-coupling reagents under palladium-catalyzed conditions was reported. Triarylbismuths as nucleophilic coupling partners were used in sub-stoichiometric amounts with respect to allylic acetates and thus served as atom-efficient multi-coupling reagents. A variety of allylic acetates were cross-coupled with triarylbismuths to furnish the corresponding functionalized 1,3-disubstituted propenes in good to excellent yields in short reaction times. The reported palladium protocol also yielded chemo-selective allylic arylations in high yields.     

Nickel(0) triethyl phosphite complex-catalyzed allylic substitution with retention of regio- and stereochemistry

Nickel(0) triethyl phosphite complex-promoted reaction of allylic acetates with thiols produced allylic sulfides with retention of configuration without allylic rearrangement. A similar reaction of allylic acetates with alcohols and phenols also proceeded with retention of regio- and stereochemistry.     

Ru3(CO)12-catalyzed intramolecular allylic transfer reaction of tethered carbonyl group and allylic acetate moiety

A ruthenium catalyzed intramolecular allylic transfer reaction of allylic acetates containing aldehydes or ketones to form cis-homoallylic cyclopentanols and cyclohexanols as a major component is described. The use of Ru₃(CO)₁₂ (1 mol %) to promote reaction results in a convenient procedure for intramolecular allylation of carbonyl functionalities.     

A Passerini/Tsuji-Trost access to dienamide derivatives

The Passerini reaction of α, β-unsaturated aldehydes affords allylic acetates which may be involved in Tsuji-Trost elimations towards conjugated dienamides. The interest of these 2,4-dienamides has been demonstrated in several TiCl₄ triggered Diels-Alder reactions with N-phenylmaleimide.     

ZnCl2-catalyzed Ferrier reaction; synthesis of 2,3-unsaturated 1-O-glucopyranosides of allylic, benzylic and tertiary alcohols

Tertiary, allylic and benzylic alcohols react with 3,4,6-tri-O-acetyl-d-glucal in dichloromethane at 25°C in the presence of ZnCl₂ to afford the corresponding 2,3-unsaturated-1-O-glucopyranoside acetates in 65-91% yields, with selective formation of the α-anomer.     

Palladium-catalyzed diastereoselective synthesis of homoaldol equivalent products

A palladium-catalyzed reaction of easily accessible 3-(pinacolatoboryl)allyl acetates and aldehydes provides facile access to synthetically useful homoaldol equivalent products with high diastereoselectivity. The reaction presumably proceeds via allylation of aldehydes with α-acetoxy allylboronates that produced in situ by reductive elimination from allylic gem-palladium/boryl intermediates.     

Palladium-catalyzed deracemization of allylic carbonates in water with formation of allylic alcohols: hydrogen carbonate ion as nucleophile in the palladium-catalyzed allylic substitution and kinetic resolution

The palladium-catalyzed deracemization of racemic cyclic and acyclic allylic methyl carbonates in water in the presence of N,N'-(1R,2R)-1,2-cyclohexanediylbis[2-(diphenylphophino)benzamide] proceeds with high enantioselectivities to give the corresponding allylic alcohols in high yields. This deracemization involves a palladium-catalyzed allylic substitution with the in-situ-formed hydrogen carbonate ion and an irreversible decomposition of the intermediate allylic hydrogen carbonates, with formation of the corresponding allylic alcohols. The palladium-catalyzed reaction of racemic cyclic allylic acetates with potassium hydrogen carbonate in water in the presence of the chiral bisphosphane proceeds with a highly selective kinetic resolution to give the corresponding allylic alcohols and allylic acetates.     

Carbon-13 pulse Fourier transform NMR : Conformational preference of the hydroxyl and the acetoxyl group in 2-cyclohexenol and its acetate

¹³C Fourier transform NMR spectra of cis and trans 5-t-butyl-2-cyclohexenols, 2-cyclohexenol and their acetates have been examined indicating that the pseudo-axial orientation of the hydroxyl and the acetoxyl group at the allylic position is favoured in 2-cyclohexenol and its acetate.     

First example of the C-alkylation of indoles with Baylis-Hillman acetates

Baylis-Hillman acetates undergo S_N2′ allylic substitution with indoles in the presence of 20 mol % of indium tribromide under mild conditions to afford a new class of substituted indoles in high yields with (E)-stereoselectivity. The stereochemistry of the products was assigned by various NMR experiments.     

Alkylations allyliques catalysees au nickel

Stable enolates such as diethyl malonate enolate can be smoothly substituted by allylic acetates (or sulfones) in the presence of nickel complexes. Sulfinate ions convert allylic acetates into sulfones.     

The allylic nucleophilic substitution of Morita-Baylis-Hillman acetates with isocyanides: a facile synthesis of trisubstituted olefins

Morita-Baylis-Hillman acetates undergo smooth allylic nucleophilic substitution (S_N2′) with tosylmethyl isocyanide (TosMIC) in the presence of a catalytic amount of BF₃·OEt₂ under mild conditions to furnish trisubstituted olefins in high yields with (E)-stereoselectivity.     

Palladium-catalyzed allylic nucleophilic substitution reactions of (E)-γ-acetoxy-α,β-unsaturated p-tolylsulfoxides

Regio- and diastereoselective nucleophilic allylic substitutions of optically pure (E)-γ-acetoxy-α,β-unsaturated p-tolylsulfoxides 2 and 3 with sodium dimethyl malonate have been carried out. The reactivity of these substrates is controlled by both the chiral sulfinyl group and the size of the alkyl group attached at the γ-terminus of the allylic system. This process constitutes an example of palladium-mediated resolution of a 1:1 mixture of acetates 2 and 3.