Addition of some α-halo ethers to unsaturated compounds

Summary The addition was carried out of 2-acetoxyethyl chloromethyl ether and of 2-chloroethyl chloromethyl ether to isobutene, to allyl chloride, to styrene, and to allyl acetate and also of 2-acetoxyethyl chloromethyl ether to butadiene and to ethyl cinnamate.     

Addition of polyfluoropolyhaloethanes to alkenes

In the presence of CrCl3/Fe redox system, polyfluoropolyhaloethanes readily added to electron-deficient or electron-rich alkenes, giving the corresponding 1:1 hydropolyfluoroalkyla-tion product or 1:1 adduct in high yields. This reaction provided a simple and convenient method to synthesize building blocks containing a CF3 or CF2 moiety.     

Indium-Mediated Addition of α-Bromoketone to Aldimines

Asanewandusefulreagentinsyntheticchemistry,indiummetalhasarousedmuchinterestinrecentyears.TheuseofindiummetalinReformatskyreactionandinBarbiertypereactionwithcarbonylcompoundshasbeendocumented.ThecyclopropanationofcarbonylcomPoundsbylndiumhasbeenknown3-TheallylationofaldiminesbyindiumundersimpleBarbiertypeconditlonshasalsobeenreported'.Howevertheuseofindiuminorganicsyn-thes1shasnotreceivedadequateattentiondespiteitslowcostandavailability.Oneofthemostobvlousadvantagesoftheindium-mediatedreact…     

Stereoselective Addition of Methyl Acrylate to α-Amino Aldehydes

Variously N-protected α-aminoaldehydes exhibit reasonable diastereoselectivity in the Baylis-Hillman coupling¹ with methyl acrylate to provide either primarily syn or anti α-methylene-β-hydroxy-γ-amino esters.     

Direct Catalytic Asymmetric Addition of α-Fluoronitriles to Aldehydes

A fluorine-containing tetrasubstituted stereogenic center is a highly valued structural feature in medicinal chemistry. Herein, we describe the direct coupling of racemic α-fluoronitriles and aldehydes promoted by a chiral Cu^I/Barton's base catalytic system, delivering α-tetrasubstituted α-fluoro-β-hydroxynitriles with satisfactory stereoselection. The stereochemical course was positively biased by the combined use of asymmetrical achiral thiourea as a supplementary ligand for Cu^I, which significantly enhanced the stereoselectivity. Both aromatic and aliphatic aldehydes were implemented to provide densely and stereoselectively functionalized chiral building blocks with aliphatic and aromatic tails.     

Addition of Allylindium Reagents to α-Iminotrifluoroethyl-phosphonates: Synthesis of CF3-Containing α-Aminoalkylphosphonates

Treatment of α-iminotrifluoroethylphosphonates with allylindium reagents in the presence of acetic acid afforded the corresponding CF₃ -containing α-aminoalkylphosphonates in high yields (83–97%) under mild conditions.     

Addition of esters of nitroacetic acid to α,β-unsaturated ketones

Summary The addition reaction of esters of nitroacetic acid to, -unsaturated ketones was studied, and new esters of ketonitroacids were prepared.     

Mild hydrolytic cleavage of α-ferrocenylalkyl-O-methyl ethers

The conversion of α-ferrocenylalkyl-O-methyl ethers into the corresponding alcohols was successfully achieved by solvolysis in water/acetone mixtures. The content of water in the solvent markedly influenced the reaction rates. The reactivity of structurally different classes of ferrocenyl ethers was evaluated and in most cases high yields of ferrocenyl alcohols or diols were obtained in a few hours without any additive. Deprotection of less reactive substrates was accelerated in the presence of montmorillonite. The method is simple, environmentally benign and valuable in providing easy access to a variety of ferrocenyl derivatives through the use of the –O-methyl ether protective group.     

A new approach to the synthesis of cyclic ethers via the intermolecular allylation of α-acetoxy ethers and ring-closing metathesis

A concise synthesis of the isolaurepinnacin skeleton 6 was achieved via the intermolecular allylation of the α-acetoxy ether 3 followed by ring-closing metathesis. This methodology was successfully applied to the convergent synthesis of the oxocene 15, an advanced synthetic intermediate for the total synthesis of laurencin.     

Addition of indoles to oxyallyl cations for facile access to α-indole carbonyl compounds

A direct coupling of unprotected indoles and α-halo ketones via in situ generated oxyallyl cation intermediates is described. The reactions efficiently afford α-indole carbonyl compounds with good to quantitative yields.     

Silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes giving approach to chalcones

A silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes is reported. The method, with a wide range of substrate tolerance and mild operational conditions, can produce various chalcone derivatives in moderate to high yields from easily available starting materials.     

Amberlyst-15 Catalyzed Addition of Phenols to α,β-Unsaturated Ketones

Amberlyst-15 has been used to catalyze regioselective additions of phenols to α,β-unsaturated ketones in yields of 20–90%. The reaction is superior to the analogous reaction employing concentrated sulfuric acid in affording greater yields and purer products with a minimum of laboratory operations.     

Catalytic Enantioselective Direct Aldol Addition of Aryl Ketones to α-Fluorinated Ketones

The catalytic enantioselective synthesis of α-fluorinated chiral tertiary alcohols from (hetero)aryl methyl ketones is described. The use of a bifunctional iminophosphorane (BIMP) superbase was found to facilitate direct aldol addition by providing the strong Brønsted basicity required for rapid aryl enolate formation. The new synthetic protocol is easy to perform and tolerates a broad range of functionalities and heterocycles with high enantioselectivity (up to >99:1 e.r.). Multi-gram scalability has been demonstrated along with catalyst recovery and recycling. ¹H NMR studies identified a 1400-fold rate enhancement under BIMP catalysis, compared to the prior state-of-the-art catalytic system. The utility of the aldol products has been highlighted with the synthesis of various enantioenriched building blocks and heterocycles, including 1,3-aminoalcohol, 1,3-diol, oxetane, and isoxazoline derivatives.     

SmI3-Catalyzed Addition of Amines to α,β-Unsaturated N-Acylbenzotriazoles

The addition of amines to α,β-unsaturated N-acylbenzotriazoles could be catalyzed by samarium triiodide (SmI₃) at ambient temperature. α,β-Unsaturated aliphatic N-acylbenzotriazoles afforded bis-addition products (β-amino amides), whereas N-cinnamoylbenzotriazoles gave acylated products (cinnamoylamides) exclusively.     

Catalytic Asymmetric Conjugate Addition of Indolizines to α,β-Unsaturated Ketones

A catalytic enantioselective conjugate addition of indolizines to enones is described. The chiral phosphoric acid (S)-TRIP activates α,β-unsaturated ketones, thereby promoting an enantioface-differentiating attack by indolizines. Using this reaction, several alkylated indolizines were synthesized in good yields and with enantiomeric ratios of up to 98:2.