Unusual reaction of β-hydroxy α-diazo carbonyl compounds with TsNHNCHCOCl/Et3N

The reaction of β-hydroxy α-diazo carbonyl compounds with TsNHNCHCOCl/Et₃N gave β-(p-tolylsulfonyl) α,β-unsaturated carbonyl compounds or β-(p-tolylsulfonyl) α-diazo esters. The reaction mechanism is discussed.     

Borohydride reducing agent derived from anion exchange resin: selective reduction of α, β-unsaturated carbonyl compounds.

Borohydride exchange resin (BER) exhibited selectivity in the reduction of α, β-unsaturated carbonyl compounds to the corresponding unsaturated alcohols.     

A Convenient Synthesis of β-Amino Acid

We have reported the reductive cleavage of azlactones¹ and phenylhydrazones² of carbonyl compounds in the presence of a suitable catalyst. In this paper a general method involving a one step synthesis of β-amino acid^3,4, in good yield, through catalytic reduction of oximes of α-β-unsaturated acid is reported. This method involves the reaction of α, β-unsaturated acid with hydroxylamine hydrochloride in the presence of sodium acetate. Markovnikov's rule is followed in the synthesis of oximes of α, β-unsaturated acids.     

Copper-catalyzed β-boration of α,β-unsaturated carbonyl compounds with tetrahydroxydiborane

The copper-catalyzed β-boration of α,β-unsaturated carbonyl compounds with tetrahydroxydiborane has been developed. This diboron reagent allows direct, efficient access to boronic acids and their derivatives. Primary, secondary, and tertiary α,β-unsaturated amides are converted to the corresponding β-trifluoroboratoamides in good to excellent yields. The β-boration of a variety of α,β-unsaturated esters and ketones is also reported.     

Keggin类杂多化合物催化α,β-不饱和羰基化合物环氧化

在乙睛溶剂中考察了一系列杂多化合物和过氧化氢水溶液催化的各种缺电子的α,β-不饱和羰基化合物的环氧化反应.在所研究的杂多化合物中,二缺位的[γ-SiW10(H2O)2O34](Bu4N)4显示出了最高的活性.     

Generation and Michael Reaction of 1, 3-Bis(trimethylsiloxy)-isoindoles by Reduction of N-Alkylphthalimides with a Zn-Me3SiCl-Lutidine System

Formation and concomitant Michael reaction of 1,3-bis(trimethylsiloxy)isoindoles have been achieved by the reduction of phthalimides with a Zn-Me₃SiCl-lutidine system in the presence of α, β-unsaturated carbonyl compounds under sonication.     

Réaction du diméthylcuprate de lithium avec les dérivés carbonylés α,β-insaturés α-fluorés et α-chlorés

Depending on the nature of the halogen, α-fluoro- and α-chloro-α,β-unsaturated carbonyl compounds (whose reduction potentials are greater than ? 2.4V) react in different ways with lithium dimethylcuprate. With α-fluoro derivatives, both 1,2- and 1,4-addition is observed, their ratios depend on the steric hindrance of the β-position. 1,4-Addition products are obtained from aldehydes and β-monosubstituted α-chloro-α,β-ethylenic ketones and esters. β,β-Disubstituted α-chloro ketones and esters give only reduction of halogen via halogen-metal exchange.     

Fluoroboric acid adsorbed on silica-gel (HBF4-SiO2) as a new, highly efficient and reusable heterogeneous catalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds

Fluoroboric acid adsorbed on silica-gel (HBF₄-SiO₂) has been found to be a new and highly efficient heterogeneous catalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds under solvent-free conditions. In the case of 1,3-diaryl-2-propenones, the reactions are best carried out in MeOH. The rate of thia-Michael addition was dependent on the steric hindrance at the β-carbon of the α,β-unsaturated carbonyl substrate as well as surrounding the thiol moiety and was exploited for selective thia-Michael addition during intermolecular competition between two enones with a common thiol and between two aryl/alkyl thiols for a common enone. The methodology finds application for one-pot syntheses of 2,3-dihydro-1,5-benzothiazepines.     

Infrared spectra and structure of substituted unsaturated carbonyl compounds: XVII. Enamino ketone and aldehyde quaternary ammonium salts

The β-trialkylammonium chloride derivatives of several α,β-unsaturated carbonyl compounds have been shown by infrared spectra to exist in the s-cis and s-trans rotational forms. The equilibrium between these two forms shifts towards the s-cis with the increasing steric requirements of the alkyl substituent linked to carbonyl. The CO and CC stretching frequencies are shifted to higher values as compared with other types of α,β-unsaturated ketones.     

Enantioselective Synthesis of β-Amino Acid Derivatives Enabled by Ligand-Controlled Reversal of Hydrocupration Regiochemistry

A Cu-catalyzed enantioselective hydroamination of α,β-unsaturated carbonyl compounds for the synthesis of β-amino acid derivatives was achieved through ligand-controlled reversal of the hydrocupration regioselectivity. While the hydrocupration of α,β-unsaturated carbonyl compounds to form α-cuprated species has been extensively investigated, we report herein that, in the presence of an appropriate ancillary chiral ligand, the opposite regiochemistry can be observed for cinnamic acid derivatives, leading to the delivery of the copper to the β-position. This copper can react with an electrophilic aminating reagent, 1,2-benzisoxazole, to provide enantioenriched β-amino acid derivatives, which are important building blocks for the synthesis of natural products and bioactive small molecules.     

Lithium n-benzyltrimethylsilylamide (LSA): a new reagent for conjugate addition - enolate trapping reactions

Lithium N-benzyltrimethylsilyl amide (LSA) adds to crotonates in a 1,4-manner, though the reaction of ordinary lithium amides with α,β-unsaturated carbonyl compounds is accompanied with a 1,2-addition and hydrogen abstraction at the γ-position. The conjugate addition via LSA followed by enolate trapping with electrophiles produces the corresponding α-substituted β-amino esters, which are, in turn, converted into β-lactams and α-substituted α, β-unsaturated esters.     

β-Phenylseone α,β-Unsaturated Aldehydes,Efficient Three Carbon Homologating Agents. 1,3-Carbonyl Transposition

The easily obtained β-phenylseleno α,β-unsaturated aldehydes react with Grignard reagents and with n-butyllithium leading to the 1,2-addition products, which upon acidic hydrolysis in the presence of silica gel afford the selenium-free α,β-unsaturated carbonyl compounds with 1,3-carbonyl transposition.     

Palladium-catalyzed conjugate reduction of α-β-unsaturated carbonyl compound with tributyltin hydride. The promoting influence of the presence of protonic or lewis acids.

Acetic acid or ZnCl₂ promote the palladium-catalyzed selective conjugate reduction of α,β-unsaturated carbonyl compounds with tributyltin hydride. Protonic agents also promote the palladium-catalyzed hydrogenolysis of aryl allyl ethers and allyl carbamates.     

Synthesis of 4,6-disubstituted 2-methylpyridines and their 3-carboxamides

A new one-pot synthesis of title compounds by the reactions of α,β-unsaturated carbonyl compounds with β-aminocrotononitrile in the presence of sodium hydroxide is described.     

An Effective Synthesis of β- Selenium and β- Tellurium Carbonyl Compounds Via Reaction of Diaryldiselenides Or Diarylditellurides with α,β- Unsaturated Carbonyl Compounds Induced by Low-Valent Titanium

P-Selenium and β-tellurium carbonyl compounds have been prepared in good yield by reaction of diaryldiselenides or diarylditelluride with α,β-unsaturated carbonyl compounds induced by TiC1₄ / Sm /THF system under mild reaction conditions.     

t-Butyldiphenylsilyl-Lithium and Lithium Bis(t-Butyldiphenylsilyl)Cuprate. New Silylating Reagents

t-Butyldiphenylsilyl-lithium reacts with carbonyl derivatives to give α -hydroxysilanes in high yields. Lithium bis (t-butyldiphenylsilyl)cuprate reacts with α, β-unsaturated ketones and esters and with acyl chlorides to give β-silylcarbonyl1 compounds and acylsilanes. β-t-Butyldiphenylsilylketones are masked α, β-unsaturated ketones.     

The Rearrangement of α-Acetylenic Alcohols to α, β-Unsaturated Carbonyl Compounds by Silylvanadate Catalysts

New catalytic systems have been found which effect the isomerization of α-acetylenic alcohols to the corresponding α, β-unsaturated carbonyl compounds with high efficiency. These are combinations of silylvanadates with silanols or silanediols.     

温和条件下离子液体／水两相体系中α，β-不饱和羰基化合物的环氧化反应研究

在室温下，以双氧水为氧化剂，研究了六氟磷酸1—甲基—3—烷基咪唑离子液 体与水构成的两相体系内α，β-不饱和羰基化合物的环氧化反应，详细考察了反 应时间、NaOH浓度、氧化剂用量和不同底物对反应结果的影响，并对其反应机理进 行了探讨。此催化体系同传统的相转移催化体系相比，实验操作简单，反应条件更 加温和，并且有效地抑制了反应过程中环氧化合物的开环，在较为适宜的反应条件 下，甲基戊烯酮转化率达到100％，环氧化选择性可达98。     

Mild Regioselective Catalytic Hydrogenation of α,β-Unsaturated Carbonyl Compounds with Lindlar Catalyst

The hydrogen-Lindlar catalyst system is effective for the highly regioselective reduction of α,β-unsaturated carbonyl compounds to the corresponding α,β-saturated compounds.     

Conjugate addition of organocopper reagents to n-tosylated α, β-unsaturated amides

N-Tosylated α, β-unsaturated amides and lactams undergo facile conjugate addition with R²CuLi or RMgX/CuI (cat.). Stereoselective synthesis of trans-β,γ-dialkyl-γ-lactams can be achieved by this procedure. The resulting N-tosylamide moiety is further transformed to alcohol and several carbonyl compounds by way of reduction or nucleophillic displacement.