Efficient Synthesis of Polyethylene Glycol Mono‐Carboxylate via Michael Conjugate Addition

Abstract

Poly(ethylene glycol) (PEG) with one carboxylate group, the very useful precursors for the synthesis of the PEG derived heterobifunctional linkers, are synthesized in high yield in one‐pot via Michael conjugate addition of acrylate esters with PEG and catalyst amount of sodium in THF.     

Simple and Efficient One‐Pot,Three‐Component,Solvent‐Free Synthesis of β‐Enaminones via Sonogashira Coupling–Michael Addition Sequences

A simple, efficient, and environmentally friendly one‐pot, three‐component synthesis of β‐enaminones via Sonogashira coupling–Michael addition sequences under solvent‐free conditions has been reported. Also the synthesis of β‐enaminones has been achieved in high yields by the direct reaction of amines with ynones under solvent‐free conditions.     

Synthesis of Novel Oxime Functionalized Aldol Products via Michael Addition of Oximes Onto Baylis–Hillman Adducts

Triphenylphosphine‐catalyzed Michael addition of oximes 2 onto Baylis–Hillman (B‐H) adducts 1 led to an easy access to a novel class of oxime functionalized aldol products 3. This demonstrates the first use of an oxygen‐centered nucleophile in Michael addition to B‐H adducts, without touching any other functional group. Deprotection of oxime in 3 was further demonstrated using molecular hydrogen (1 atm) and 10% Pd/C (cat.) to furnish functionalized 1,3‐diols 4 as potentially useful synthons with optional backbone choice (R³ and EWG).     

Catalytic Asymmetric Friedel–Crafts Alkylation of Indole via In Situ Generated Indol-2-one

An asymmetric Friedel–Crafts alkylation of indole with in situ generated indol-2-one from functionalized 3-bromooxinidole catalyzed by chiral N,N’-dioxide/Ni(BF₄)₂ has been developed. This protocol provides an efficient route to stereoselective construction of a series of 3-substituted 3’-indolyloxindoles bearing a quaternary carbon center in excellent yields and enantioselectivities (up to 99 % ee). In addition, the conversion of the resulted 3-substituted 3’-indolyloxindole to the key intermediate for the formal synthesis of (+)-folicanthine was also demonstrated.     

Simple and Efficient One-Pot Synthesis of Nitriles from Amides and Oximes Using in Situ–Generated Burgess-Type Reagent

The dehydration of aldoximes and amides, and oxidation of benzoin are accomplished in one-pot using in situ–generated Burgess-type reagent.

Modified One-Pot Multicomponent Diastereoselective Synthesis of Trans-2,3-Dihydrofuro[3,2-c]coumarins via In Situ–Generated α-Tosyloxyketones

A modified protocol for diastereoselective synthesis of differently substituted trans-2,3-dihydrofuro[3,2-c]coumarins is developed via, a one-pot multicomoponent reaction starting from aromatic aldehydes, 4-hydroxycoumarin, and α-tosyloxyacetophenones with pyridine and triethylamine as catalysts. The developed protocol provides a better alternative to the existing methods as it involves utilization of α-tosyloxyacetophenones that may be generated in situ from acetophenones and [hydroxyl(tosyloxy)iodo]benzene (HTIB, Koser's reagent), avoiding the use of α-haloacetophenones.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

One-Pot Synthesis of 3,4-Dihydropyrimidine-2-(1H)-ones Using CsF–Celite as Catalyst

A facile, efficient, and environmentally benign procedure for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via the cyclocondensation reaction of aromatic aldehyde, ethyl acetoaceate, and urea catalyzed by CsF–Celite was developed. This environmentally friendly method is superior to previous methods with respect to reaction time, yield, and workup.     

Synthesis of β-Amino Phosphonates in One-Pot Procedure

Abstract: β-amino phosphonate derivatives are synthesized in one-pot procedure via reduction of β-enamino phosphonate intermediates with NaBH₄/acetic acid or trifluoroacetic acid.     

Synthesis of Arylsubstituted Imidazolin-2-one Analogues

Herein we reported a one-pot synthesis of arylsubstituted imidazolin-2-ones by thecyclization of ct-aminoacetophenone hydrochloride analogues 2 with arylisocyanates 3. Comparedwith other known synthetic route, this method resulted in higher yield.     

Novel Sulfamic Acid–Promoted Synthesis of 3-Alkylidene Indolone Derivatives in the Presence of Aniline via One-Pot Multicomponent Reaction

A sulfamic acid–catalyzed synthesis of 3-alkylidene indolone derivatives by addition of dialkyl acetylenedicarboxylate to isatin derivatives in the presence of aniline is reported. The reaction sequence consists of an initial Michael addition of aniline to dialkyl acetylenedicarboxylate, followed by aldol-like reaction with isatin, and then elimination of aniline to afford the product.     

Ionic Liquid–Catalyzed One-Pot Synthesis of 1H-Pyrano[2,3-d]pyrimidin-2(8aH)-one Derivatives via Three-Component Reaction under Solvent-Free Conditions

A series of 1H-pyrano[2,3-d]pyrimidin-2(8aH)-one derivatives were synthesized via one-pot, three-component reaction of aromatic aldehydes, urea or thiourea, and 3,4-dihydro-2H-pyran using the green and inexpensive Brønsted acidic ionic liquid 1-methyl-2-pyrrolidinone hydrosulfate ([Hnmp]HSO₄) as catalyst under solvent-free conditions. The method has several advantages such as mild conditions, shorter reaction time, good yields, and environmentally benign procedure. Moreover, the catalyst could be recovered conveniently and reused at least four times without evident loss of activity.     

A Facile One-Pot Synthesis of 2,3′-Anhydro-2′-Deoxyuridines via 3′-O-Imidazolylsulfonates

Continued interests in the novel synthetic methods of the pivotal compound, 2,3′-anhydro-2′-deoxyribonucleosides (7) uncovered a facile one-pot conversion of 5 with 1,1′-sulfonyldiimidazole in basic conditions to 7 with almost quantitative yields (91–99%).     

Ammonium Chloride–Catalyzed One-Pot Synthesis of Tetrahydrobenzo[α]xanthen-11-one Derivatives Under Solvent-Free Conditions

A one-pot, multicomponent reaction of aldehydes, dimedone, and β-naphthols is described for the preparation of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[α]xanthen-11-one derivatives using ammonium chloride as a mild, inexpensive, and environmentally benign catalyst under solvent-free conditions. Different types of aldehyde and β-naphthol derivatives are used in the reaction, and in all cases the products were synthesized successfully.

Cerium Alkoxides—Synthesis, Properties and Their Use in Michael Addition Reaction

Cerium(III) alkoxides served as an effective and attractive promoter for the Michael addition reaction with excellent chemical yields under mild conditions in short reaction time.     

Solvent-Free One-Pot Synthesis of Spiro[indoline-3,4′(1H′)-pyrano[2,3-c]pyrazol]-2-one Derivatives by Grinding

The solvent-free one pot synthesis of spiropyranyl-oxindole in the presence of NaHCO₃ under grinding has been achieved. This process is simple, fast, efficient and environmentally benign.      

The Michael Addition of Enamines to Propenamidines. A Convenient Synthesis of 2β-Amidinoethylcyclo-Alkanones by Amidinoethylation Reaction

A variety of propenamidines 3 have been reacted with enamines of cyclopentanone and cyclohexanone giving after hydrolysis of the Stork enamine 6, 2-β-amidinoethylcyclopentanones 8 and -hexanones 7. This reaction illustrates the electrophilic character of the C=C double bond due to the conjugated amidine function, thus providing with propenamidines 3 a new class of Michael acceptors for enamines.     

DBU(OAc)–TBAB-Mediated One-Pot Three-component Synthesis of 1H-Imidazol-5(4H)-one Derivatives

Russian Journal of Organic Chemistry - One-pot three-component synthesis of 1H-imidazol-5(4H)-one derivatives from (Z)-4-(aryl­methylidene)-2-methyl-1,3-oxazol-5(4H)-one, methylamine, and...     

A Short,Convenient Synthesis of 2-Arylglycidates via Aryl-Grignard Addition to an α-Bromopyruvate

A simple procedure has been developed for the preparation of a series of 2-arylglycidates required for herbicidal evaluation. Treatment of the α-bromopyruvate 5 with various aryl Grignard reagents at low temperature gave directly the glycidates 4. Saponification of these then afforded the desired sodium salts 7.     

Synthesis of Chiral Benzimidazole‐Pyrrolidine Derivatives and their Application in Organocatalytic Aldol and Michael Addition Reactions

An efficient and mild approach for the synthesis of pyrrolidine‐benzimidazoles has been reported. They were further employed for the aldol and Michael addition reactions to afford the corresponding products with good yields and moderate enantioselectivities.