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Upstream product

• 2564-83-2 2,2,6,6-tetramethyl-piperidine-N-oxyl 
• 93-55-0 1-phenyl-propan-1-one 
• 2564-83-2 2,2,6,6-Tetramethyl-1-piperidinyloxy free radical 
• 6084-17-9 2-chloro-1-phenylpropan-1-one 
• 2114-00-3 2-bromo-1-phenyl-1-propanone 
• 863309-36-8 2,2,6,6-tetramethylpiperidine-1-oxoammonium hexafluorophosphate 

Relevant academic research and scientific papers

Visible-Light-Enabled Enantioconvergent Synthesis of α-Amino Acid Derivatives via Synergistic Br?nsted Acid/Photoredox Catalysis

An unprecedented radical cross-coupling reaction was achieved between glycine esters and racemic α-bromoketones catalyzed by synergistic Br?nsted acid/photoredox catalysis, thus serving as an efficient platform for the synthesis of highly valuable enantioenriched unnatural α-amino acid derivatives. This dual catalysis provides a powerful capability to control the reactive radical intermediate and iminium ion, thereby enabling enantioconvergent bond-formation in a highly stereochemical manner. An array of valuable enantioenriched unnatural α-amino acid derivatives bearing two contiguous stereogenic centers are readily accessible with high diastereoselectivity and excellent enantioselectivity, which include α-amino acids with a unique β-fluorinated quaternary stereocenter or its β-all-carbon counterpart. A strong chiral amplification effect was observed in this dual catalytic system.

Intermolecular Multiple Dehydrogenative Cross-Couplings of Ketones with Boronic Acids and Amines via Copper Catalysis

An efficient and versatile oxidative coupling reaction was developed for the synthesis of valuable β-functionalized unsaturated ketones and meta-substituted phenols. In the case of intramolecular reactions, achieving rapid molecular complexity through multiple dehydrogenative couplings is already a well-established strategy. Herein, we report an intermolecular multiple dehydrogenative coupling between ketones and nucleophilic amines or boronic acids using inexpensive copper(I) oxide as a catalyst. This method provides a facile access to highly desirable chemical products such as α,β-unsaturated ketones, enaminones, and synthetically relevant meta-substituted phenols. (Figure presented.).

Fe-Catalyzed enaminone synthesis from ketones and amines

We have developed an iron-catalyzed direct olefination for enaminone synthesis, with saturated ketones as a source of olefins. This direct ketone β-functionalization reaction has readily available starting materials and a wide range of substrates and requires mild reaction conditions.

Iron Catalysis for Modular Pyrimidine Synthesis through β-Ammoniation/Cyclization of Saturated Carbonyl Compounds with Amidines

An efficient method for the modular synthesis of various pyrimidine derivatives by means of the reactions of ketones, aldehydes, or esters with amidines in the presence of an in situ prepared recyclable iron(II)-complex was developed. This operationally simple reaction proceeded with broad functional group tolerance in a regioselective manner via a remarkable unactivated β-C-H bond functionalization. Control experiments were performed to gain deep understanding of the mechanism, and the reactions are likely to proceed through a designed TEMPO complexation/enamine addition/transient α-occupation/β-TEMPO elimination/cyclization sequence.

Domino Radical Addition/Oxidation Sequence with Photocatalysis: One-Pot Synthesis of Polysubstituted Furans from α-Chloro-Alkyl Ketones and Styrenes

A new domino reaction has been developed that allows the combination of styrenes and α-alkyl ketone radicals to afford a wide array of polysubstituted furans in good to excellent yields under mild and simple reaction conditions. The key to success of this novel protocol is the use of photocatalyst fac-Ir(ppy)3and oxidant K2S2O8. Mechanistic studies by a radical scavenger and photoluminescence quenching suggest that a radical addition/oxidation pathway is operable.

Facile and highly diastereoselective synthesis of syn- and cis-1,2-diol derivatives from protected α-hydroxy ketones

An efficient method for the synthesis of monoprotected syn- or cis-1,2-diol derivatives by reduction of easily accessible α-(2,2,6,6-tetramethylpiperidinyloxy) ketones is reported. The α-(tetramethylpiperidinyloxy) group as the stereodirecting group induces in unhindered acyclic or cyclic ketones complete syn- or cis-diastereoselectivity, respectively, with L-Selectride. For more hindered derivatives, where L-Selectride becomes unreactive, LiAlH4 proved effective, essentially showing the same high selectivity. The diastereoselectivity of the reduction can be rationalized for acyclic ketones by the Felkin-Anh model, whereas for cyclic substrates, attack from the face opposite to the tetramethylpiperidinyloxy group predictably prevails with high selectivity regardless of the substitution pattern. The liberation of free diols was achieved by reductive N-O bond cleavage of the alkoxyamine unit. Monoprotected syn- and cis-1,2-diols were synthesized by reduction of ketones bearing the stereodirecting α-(2,2,6,6-tetramethylpiperidinyloxy) group. The latter induces syn- or cis-selectivity in unhindered acyclic or cyclic ketones with L-Selectride, whereas the smaller LiAlH4 induced excellent diastereoselectivity with hindered ketones. Free 1,2-diols were liberated by reductive N-O bond cleavage.

Oxidative catalysis using the stoichiometric oxidant as a reagent: An efficient strategy for single-electron-transfer-induced tandem anion-radical reactions

Oxidative single-electron transfer-catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product. Making waste a functionality: Ox

α-aminoxylation of ketones and β-chloro-α-aminoxylation of enones with tempo and chlorocatecholborane

Oxidation of various cyclic and acyclic ketones under mild conditions with chlorocatecholborane, a bulky pyridine base, and TEMPO to the corresponding α-aminoxylated products in good to excellent yields (52-99%) is described. For enones as substrates, products of a β-chloro-α-aminoxylation are obtained (70-89%).

General and efficient α-oxygenation of carbonyl compounds by TEMPO induced by single-electron-transfer oxidation of their enolates

A generally applicable method for the synthesis of protected α-oxygenated carbonyl compounds is reported. It is based on the single-electron-transfer oxidation of easily generated enolates to the corresponding α-carbonyl radicals. Coupling with the stable free radical TEMPO provides α-(piperidinyloxy) ketones, esters, amides, acids or nitriles in moderate-to-excellent yields. Enolate aggregates influence the outcome of the oxygenation reactions significantly. Competitive reactions have been analyzed and conditions for their minimization are presented. Chemoselective reduction of the products led to either N-O bond cleavage to α-hydroxy carbonyl compounds or reduction of the carbonyl functionality tomonoprotected 1,2-diols or O-protected amino alcohols. The oxygenation of enolates proves to be the most general and effective methodology for the synthesis of O-protected α-oxy carbonyl compounds and nitriles A. The scope and limitations of the electron-transfer-induced radical coupling reaction with TEMPO are presented. The reaction pathways are outlined. Methods for the deprotection to α-hydroxy carbonyl compounds B are provided and discussed. Copyright