Stetter Reaction Research Articles

MeOPEG-Supported Carbene Catalysts

Preparation of MeOPEG resin-supported heteroazolium salts and their catalytic activities are described. Thus, heteroazoles 1 reacted with propargyl bromide to give the heteroazolium salts 2 quantitatively. Treatment of 2 with MeOPEG-supported azide in the presence of CuBr and ascorbic acid in a mixed solvent of H2O and t-BuOH afforded the desired MeOPEG resin-supported heteroazolium salts 3 (eq. 1). The intramolecular Stetter reaction of 4 with 3a in the presence of DIPEA gave chloman-4-one 5 in 84% yield (eq. 2). The reductive esterification of 3-phenyl-2-propynal 6 was carried out in the presence of 3b, DMAP, and ethanol to afford ethyl cinnamate 7 in 83% yield (E/Z > 95:5) (eq. 3).

Formal Synthesis of (.+‐.)‐Platensimycin.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An Efficient and Versatile Approach for the Immobilization of Carbene Precursors via Copper‐Catalyzed [3+2]‐Cycloaddition and their Catalytic Application

AbstractDifferent classes of alkynyl‐substituted heterazolium derivatives could be covalently immobilized on an azide‐functionalized support via copper‐catalyzed 1,3‐dipolar cycloaddition, which efficiently yields a rigid and robust 1,2,3‐triazole linkage. The catalytic performance of the corresponding nucleophilic carbenes (NHCs) was examined in intramolecular Stetter reactions (chroman‐4‐one products) and organocatalytic redox esterifications (α,β‐unsaturated esters). The MeOPEG‐immobilized organocatalysts are highly active, and show comparable diastereoselectivities to non‐supported derivatives. Additionally, they allow simplified work‐up procedures and also have proven to be recyclable.

Recent Examples of Divergent Catalysis in Organic Reactions: Unexpected Findings or Rational Design?

The term ‘divergent catalysis’ describes different catalytic chemical reactions that occur with the same substrates (reactants) under controllable conditions, especially using different catalysts. Various substrates were found to work with versatile reactivity under different catalytic conditions, resulting in the formation of different products. However, the examples of rationally designed divergent catalysis are still few. This review is focused on the achievements of divergent catalysis with the simplest substrates in the past decades. It includes divergent catalysis of one-component and two-component reactions with the same and simple reagents, ranging from carbon-carbon-forming pinacol coupling, benzoin condensation, Ullmann coupling, C-H homocoupling or activation, ring-closing metathesis, cyclization, Stetter reaction, Baylis-Hillman reaction, Friedel-Crafts reaction, C-H Heck coupling, 1,2-additon reaction and Michael addition, to the carbon-heteroatom bond-forming C-N cross coupling, hydroamination reaction, aza-Michael reaction, C-H oxidative amination, acetalization, and esterification.

Enantioselective Synthesis of Hydrobenzofuranones Using an Asymmetric Desymmetrizing Intramolecular Stetter Reaction of Cyclohexadienones.

A series of cyclohexadienones were synthesized by dearomatization of phenols followed by Dess-Martin oxidation. Asymmetric intramolecular Stetter reactions of these substrates provide hydrobenzofuranones in good to excellent yields and excellent stereoselectivities. Up to three stereocenters as well as quaternary stereocenter are formed from polysubstituted substrates. A scale up experiment demonstrates the utility of this transformation.

Enantioselective Formation of Quaternary Stereocenters Using the Catalytic Intramolecular Stetter Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An Efficient Intramolecular Stetter Reaction in Room Temperature Ionic Liquids Promoted by Microwave Irradiation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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A biosynthetic pathway sometimes breathes new life into organic chemistry with its elegant mechanistic insight. Thiamine diphosphate (ThDP) is known as a coenzyme of transketolase and catalyze acyl anion transfer reactions in vivo by exploiting the concept of polarity reversal. The active catalyst for this biological transformation is N-heterocyclic carbene (NHC) generated from ThDP. Stetter reaction is one of the useful carbon-carbon bond forming reaction, which is induced by NHC. In this review, the enantioselective version of NHC catalyzed reactions, specialized in the intramolecular Stetter reaction and its related reactions are mentioned.

Formal synthesis of (±)-platensimycin

A formal total synthesis of (+/-)-platensimycin [(+/-)-1] is reported involving an intramolecular Stetter reaction and a radical cyclization.

C2 Symmetric Chiral N‐Heterocyclic Carbene Catalyst for Asymmetric Intramolecular Stetter Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Efficient Synthesis of 3‐Substituted 2,3‐Dihydroquinolin‐4‐ones Using a One‐Pot Sequential Multi‐Catalytic Process: Pd‐Catalyzed Allylic Amination—Thiazolium Salt‐Catalyzed Stetter Reaction Cascade.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An Efficient Intramolecular Stetter Reaction in Room Temperature Ionic Liquids Promoted By Microwave Irradiation

AbstractThis communication describes the first report of a microwave‐assisted intramolecular Stetter reaction using imidazolium‐type room temperature ionic liquids (RTILs) as solvents, with thiazolium salts and Et3N as catalysts. The features such as good to excellent yields, shorter reaction time (5–20 min), and recyclable and reusable ionic liquid and catalyst make this method an environmentally benign and highly efficient procedure for the preparation of chromanone derivatives.

Enantioselective formation of quaternary stereocenters using the catalytic intramolecular Stetter reaction

Asymmetric formation of quaternary stereocenters has been accomplished using the catalytic intramolecular Stetter reaction. A variety of tethered aldehydes and Michael acceptors are cyclized in excellent yields and enantioselectivities.

C2 Symmetric chiral N-heterocyclic carbene catalyst for asymmetric intramolecular Stetter reaction

The asymmetric intramolecular Stetter reaction of ω-formyl α,β-unsaturated carbonyl compounds was catalyzed by a C2 symmetric chiral carbene, generated from (4 S,5 S)-diphenyl-1,3-bis(mesitylmethyl)-4,5-dihydro-1 H-imidazolium tetrafluoroborate, to afford 2-substituted cyclopentanones in good enantioselectivity of up to 80%.

Asymmetric Synthesis of Hydrobenzofuranones via Desymmetrization of Cyclohexadienones Using the Intramolecular Stetter Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Efficient synthesis of 3-substituted 2,3-dihydroquinolin-4-ones using a one-pot sequential multi-catalytic process: Pd-catalyzed allylic amination–thiazolium salt-catalyzed Stetter reaction cascade

We developed an efficient method for the synthesis of 3-substituted 2,3-dihydroquinolin-4-ones using a one-pot sequential multi-catalytic process: Pd-catalyzed allylic amination–thiazolium salt-catalyzed Stetter reaction cascade. Measurement of the initial rate of the developed sequential process revealed a significant increase in the reaction rate of the Stetter reaction in the presence of Pd(OAc) 2 and AcOH· i-Pr 2NEt, the constituents of the first Pd catalysis.

Asymmetric Synthesis of Hydrobenzofuranones via Enantioselective Stetter Reaction

Asymmetric Synthesis of Hydrobenzofuranones via Enantioselective Stetter Reaction

Asymmetric Synthesis of Hydrobenzofuranones via Desymmetrization of Cyclohexadienones Using the Intramolecular Stetter Reaction

Dearomatization of phenols followed by oxidation affords cyclohexadienyloxyacetaldehydes, which produce hydrobenzofuranones via asymmetric intramolecular Stetter reaction in good to excellent yield. Quaternary as well as up to three contiguous stereocenters may be formed in good to excellent enantioselectivities and high diastereoselectivities.

A Highly Enantio- and Diastereoselective Catalytic Intramolecular Stetter Reaction.

A highly enantio- and diastereoselective intramolecular Stetter reaction has been developed. Subjection of α,α-disubstituted Michael acceptors to an asymmetric intramolecular Stetter reaction results in a highly enantioselective conjugate addition and a diastereoselective proton transfer. Available evidence suggests the diastereoselective protonation occurs via intramolecular delivery to the sterically more hindered face of the enolate. The scope of the trisubstituted Michael acceptors has been examined and found to be broad with respect to the size of the α-substituent and nature of the Michael acceptor. Aliphatic and aromatic aldehydes were examined and found to afford the desired product in good overall yield with high enantio- and diastereoselectivity.

Heterocyclic α‐Alkylidene Cyclopentenones Obtained via a Pauson—Khand Reaction of Amino Acid Derived Allenynes. A Scope and Limitation Study Directed Toward the Preparation of a Tricyclic Pyrrole Library.

AbstractFor Abstract see ChemInform Abstract in Full Text.