A New Convenient Synthesis of α-Arylpropionic Acid Esters and α-Arylpropionitriles

Various types of α-arylpropionic acid esters were effectively obtained by the coupling reaction of aryl Grignard reagents and α-bromopropionic acid esters in the presence of nickel catalysts. α-Arylpropionitriles, precursors of α-arylpropionic acids, were also synthesized by the reaction of α-methanesulfonyloxypropionitrile and arylcopper reagents prepared from equimolar amount of arylmagnesium halides and copper(I) bromide.     

A Convenient Synthesis of Protected α-Hydroxyacetaldehydes

Starting from 2, 3-O-isopropylideneglycerol (1), a general procedure for the preparation of protected α-hydroxyacetaldehydes has been developed.     

A Convenient Method for the Conversion of α-Tetralones to Aryl Acetates

A facile synthesis of aryl acetates from α-tetralone has been performed with isopropenyl acetate and p-toluenesulfonic acid, followed by dehydrogenation with air or DDQ, in a one-pot procedure.     

A Convenient Route to α-Alkoxy Ester from Olefin Vla Organoborane-Catalyzed Hydroalumintaion

Organoborane-catatyzed hydroalumination of olefin with dichloroaluminum hydride and subsequent functionalization of the resulting organoaluminum with methyl α-chloro-α-methoxyacetate give rise to the corresponding α-methoxy ester in good yield.     

Synthesis of Methyl α-d-Allopyranoside and Methyl α-d-Ribo-hexopyranoside: A Convenient Chemoenzymatic Approach

Abstract

An efficient chemoenzymatic synthesis of methyl α-d-allopyranoside and methyl 3-deoxy-α-d-ribo-hexopyranoside starting from methyl 4,6-O-benzylidene-α-d-glucopyranoside is described.     

A Convenient Method of Protection and Mild Deprotection of α-Aminoacids

Functionalisation of β or γ carboxyl group of aspartic and glutamic acids with labile substituents was performed via the use of N-trichloroethoxycarbonyl5-oxazolidinone as protective group.     

Environmentally Compatible Access to α-Trifluoromethylseleno-Enones

α-Trifluoromethylselenolated enones constitute valuable building-blocks for further synthesis of innovative fluorinated compounds. Herein, we described an easy access to such compounds in green conditions through a Morita-Baylis-Hillman like reaction. These conditions have also been extended to higher fluorinated homologs.     

A Convenient and Simplified Preparation of Both Enantiomers of α-Terpinyl Chloride

Several methodologies to produce α-terpinyl chloride from “hydrochlorination” of limonene were studied and the best results were obtained by reaction with 0.5 mol equiv. SOCl₂ in SiO₂ / CH₂Cl₂. Using this methodology (R)- and (S)-α-terpinyl chloride can easily be prepared in good yields from (R)- and (S)-limonene, respectively.     

A Convenient Synthesis of α-Hydrosyiminoacetonitriles from Aldoximes

Aromatic α-hydroxyiminoacetonitriles can be conveniently prepared by a facile one-pot procedure in high yields involving chlorination of the corresponding aldoximes with tert-butyl hypochlorite followed by reaction with alkali cyanide.     

Iodoacetoxylation Reaction: A Convenient Route to α-Glycosides in the 2-Iodo and 2-Deoxy Series

Abstract

Iodoacetoxylation of 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol (tri-O-acetyl-D-glucal) (1) and 3,4-di-O-acetyl-1,5-anhydro-2,6-dideoxy-L-arabino-hex-1-enitol (di-O-acetyl-L-rhamnal) (3) gave the α-1,2-trans-1-O-acetyl-2-deoxy-2-iodo adducts with high stereoselectivities and good yields, in accordance with the results reported on 3,6-di-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-1,5-an-hydro-2-deoxy-D-arabino-hex-1-enitol (hexa-O-acetyl lactal) (2). The α-1,2-trans adducts were reacted with an excess of alcohol in the presence of trimethylsilyl trifluoromethane-sulfonate affording the corresponding α-1,2-trans-2-deoxy-2-iodo-glycopyranosides in good yields. The octyl 2-deoxy-2-iodo-α-D-glycosides 10 and 11 prepared in two steps from the glycals 1 and 2 were deiodinated and deacetylated, giving 28 and 29, and the physicochemical-properties (cmc) of 29 are reported.     

A Convenient Procedure for the Conversion of Carboxylic Acids to α-Bromo Thiolesters

Carboxylic acids can be conveniently transformed to the corresponding α-bromo thiolesters by a one-pot procedure involving Hell-Volhard-Zelinsky reaction and trapping the α-bromo acyl bromide intermediate with mercaptans.     

A Convenient Two-Step Procedure for Lactone α-Methylenation

A new procedure for lactone α-methylenation is described in which α-hydroxymethyl lactones are dehydrated with cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate-CuCl₂ in acetonitrile.     

A Convenient Synthesis of α-Hydroxyiminoacetonitriles From Aldoximes

Aromatic α-hydroxyiminoacetonitriles can be conveniently prepared by a facile one-pot procedure in high yields involving chlorination of the corresponding aldoximes with tert-butyl hypochlorite followed by reaction with alkali cyanide.     

Epoxide-Mediated Stevens Rearrangements of α-Amino-Acid-Derived Tertiary Allylic,Propargylic, and Benzylic Amines: Convenient Access to Polysubstituted Morpholin-2-ones

A new strategy has been established for the synthesis of polysubstituted morpholin-2-ones through Stevens rearrangements of tertiary amines via in situ activation with epoxides. A range of α-amino acid-derived tertiary allylic, propargylic, and benzylic amines reacted with epoxides in the presence of zinc halide catalysts to afford structurally diverse allyl-, allenyl-, and benzyl-substituted morpholin-2-ones, respectively, in moderate-to-good yields with high regioselectivity. The process involves [2,3]- and [1,2]-Stevens rearrangements of quaternary ammonium ylide intermediates and constitutes a very convenient method to prepare polysubstituted morpholin-2-ones through tandem formation of C−N, C−O, and C−C bonds. Moreover, replacing epoxides with aziridines permitted the synthesis of polysubstituted piperazin-2-ones.     

Hypervalent Iodine Oxidation of Trimethylsilyl Ketene Acetals: A Convenient Route to α-Methoxylation of Esters and Lactones

Hypervalent iodine oxidation of trimethylsilyl ketene acetals of esters and lactones using iodosobenzene in methanol affords the corresponding α-methoxylated carbonyl compounds in good yields.

     

A Convenient and Efficient Deallylation Procedure

In the Presence of NaBH4/BF3,allyl ethers underwent deallylation to the corresponding alcohols or phenols in good yield and high reaction rate.     

A General Synthesis of α-Substituted Acrylonitriles

During a study of synthetic approaches to naturally-occurring sesquiterpene lactones, a new synthesis of the α-methylene-y-butyrolactone group was developed¹ and has subsequently been applied to the synthesis of various types of α-methylenecarbonyl compounds.² The synthetic scheme suggested that α-substituted acrylonitriles would also be available by this method.     

A Convenient Reduction of α,β-Unsaturated Nitroalkenes to Alkylamines Using Boron Hydrides

α,β-Unsaturated nitroalkenes are reduced to alkylamines in good yields by excess of borane-THF in presence of catalytic amount of sodium borohydride.     

A Convenient Synthesis of α-Functional Alkyl Vinyl Ketones

Reaction of 2-functional alkyl-1,3-diketones with 30% aqueous formaldehyde using aqueous 6-10M potassium carbonate solution as base, afforded a-functional alkyl vinyl ketones in good yields.     

A Convenient Synthesis of α,β-unsaturated Nitriles

α,β-unsaturated nitriles were synthesized by the reaction of aldehydes with bromoacetonitrile promoted by tri-n-butylphosphine and zinc.