Search

Heterocycles represent the most important and diverse variety of natural products. Nowadays there are plenty of heterocycles that are known, the quantity is growing unexpectedly because of their synthetic uses and the enormous synthetic research. Heterocycles play an important role in many areas of sciences including biochemistry, medicinal chemistry and other areas of science. This field is growing and the acetamidines have gained an equally recognized position and have been developed as a common motif in organocatalysis. In this review article, we have concentrated on the synthesis of heterocycles using acetamidine. [ABSTRACT FROM AUTHOR]

An efficient and convenient Strecker-type addition of various substituted aromatic acetals, heteroaromatic acetals and α, β-unsaturated acetals with trimethylsilyl cyanide (TMSCN) is achieved catalyzed by 10 mol% of MgI2 etherate (MgI2•(Et2O)n) in a mild, and high chemoselective manner with good to excellent yields. A non-coordinating reaction media (i.e., CH2Cl2) played a vital role in this catalytic process. [ABSTRACT FROM AUTHOR]

This review is a broad overview of the chemistry of 2-tosylacetonitrile, which considered as a very reactive synthetic compound. The synthetic methods are reported. The reactions of the title compound lead to the preparation of a variety of heterocyclic ring systems, such as five- and six-membered ring systems containing one, two, or three heteroatoms. The reaction mechanisms are discussed. [ABSTRACT FROM PUBLISHER]

1-Benzyl-2-(nitromethylene)pyrrolidines in triflic acid undergo intramolecular cyclization to afford the corresponding 2,3-dihydro-1H-pyrrolo[1,2-b]isoquinolinium triflates and/or 10-amino-2,3-dihydro-1H-pyrrolo[1,2-b]isoquinolinium triflates, depending on the nature of the aromatic substituent. Structures of products and reaction mechanisms are discussed. [ABSTRACT FROM PUBLISHER]

1-(ω-Phenylalkyl)-2-(nitromethylene)pyrrolidines in triflic acid undergo a C,O-diprotonation, followed by loss of water, to form conjugated iminium–hydroxynitrilium dications, which react with the tethered phenyl ring by electrophilic aromatic substitution to afford tricyclic iminium compounds as triflate salts. The scope and mechanism of this reaction are discussed. [ABSTRACT FROM AUTHOR]

In this article, a practically interesting route for the diastereoselective synthesis of phenylpropanolamines has been demonstrated for the first time. Using racemicO-tert-butyldiphenylsilyl (TBDPS) cyanohydrins as the starting materials, varioussynphenylpropanolamines and derivatives (e.g., norpseudophedrine) have been successfully prepared in exellent diastereoselectivity via a practically interesting process. [ABSTRACT FROM AUTHOR]

An extension of our methodology on solid-phase synthesis (SPS) of five-membered heterocycles to functionalized tetronic acids is reported. The key step of our methodology is the application of a carbonate linker to the synthesis, offering us the convenience of incorporating the starting material and cleavage under mild conditions. The products were obtained in satisfactory yields and purities. The developed method can be applied to the preparation of libraries containing the tetronic acid moiety. [ABSTRACT FROM AUTHOR]

The interaction of different 3-acetylfuran-2(5H)-ones (1, 4) with dimethylformamide dimethyl acetal (DMF/DMA) has been investigated, and the condensed furopyridine system 3 was obtained. By means of interaction of compounds 4 and DMF/DMA via the 3-acetylfuran-2(5H)-one enamines, the heterocyclic substituted furanones are obtained. The condensation of 3-acetyl-4,5,5-trimethylfuran-2(5H)-one (1a) with veratraldehyde was realized. Through the interaction of 1a with malononitrile and further intramolecular condensation of the product, 6-amino-dihydroisobenzofuran-5-carbonitrile was also synthesized. [ABSTRACT FROM PUBLISHER]

[image omitted] Reaction of arylmethyl/heteryl methyl zinc chloride (generated in situ from aryl methyl and heteryl methyl chloride and zinc metal) with aryl sulfonyl chlorides in tetrahydrofuran (THF) under mild conditions (i.e., at room temperature) furnishes the corresponding 1-(aryl sulfonyl)aryl/heteryl methanes in good yields. [ABSTRACT FROM AUTHOR]

[image omitted] Friedel-Crafts acylation of aromatic ethers, anisole, 2-methoxynaphthalene, and dimethoxybenzenes with different acid anhydrides is carried out in the presence of an inexpensive and nonhazardous solid acid, Amberlyst 15. The catalyst is reusable, thus making the process environmentally friendly. [ABSTRACT FROM AUTHOR]

Friedel-Crafts-type acylation of phenyl ether with 2,5-dichlorobenzoic acid could be accomplished in a single step using trifluoroacetic anhydride and phosphoric acid. The method gave a greater yield (78%) than the conventional two-step process (71%) of acid chloride generation followed by aluminum trichloride-mediated acylation. [ABSTRACT FROM AUTHOR]

2-Arylethylamine derivatives were synthesized using the Curtius reaction and with three different methods of preparing the acyl azide functional group. Carbamates derived from isocyanate were convenient protecting groups for alkylation of amines. Starting from benzaldehyde, amphetamine was prepared in three steps through an oxazolidin-2-one intermediate in 62% overall yield. [ABSTRACT FROM AUTHOR]

A simple and efficient protection of alcohols as trityl ethers is described using trityl chloride in the presence of 5 mol% FeCl3 as catalyst in ionic liquids at room temperature in shorter reaction times. This mild and efficient method gives access to the protection of a wide range of alcohols in good yields. The use of ionic liquid allows easy separation of the product and recycling of catalyst. [ABSTRACT FROM AUTHOR]

An efficient and chemoselective method for the Friedel-Crafts acylation of aromatic compounds using P2O5/Al2O3 and carboxylic acids. Both aromatic and aliphatic carboxylic acids reacted easily to afford the corresponding aromatic ketones in good yields. [ABSTRACT FROM AUTHOR]

The alkali salt of L-proline was demonstrated to be an efficient and practical catalyst for the cyanosilylation of a wide variety of simple and functionalized carbonyl compounds under solvent-free conditions. The reactions proceeded smoothly at room temperature to afford the corresponding cyanohydrins in good to excellent yields. [ABSTRACT FROM AUTHOR]

Cyanosilylation of various aldehydes and ketones with TMSCN proceeded smoothly under mild conditions to give the corresponding cyanohydrin trimethylsilyl ethers in the presence of nanocrystalline magnesium oxide. The cyanohydrin trimethylsilyl ethers of aldehydes produced cyanohydrins in good to high yields on treatment with 2 N HCl. 29Si NMR spectral evidence proved that the reaction proceeds through the hypervalent silicate species by coordination to O2-/O- (Lewis basic site) of nanocrystalline magnesium oxide. [ABSTRACT FROM AUTHOR]

Zn(OTf)2 · 6H2O was used to promote Friedel-Crafts acylation of aromatics. The work describes the high activity and efficiency of Zn(OTf)2 · 6H2O in acylation of aromatics, and the catalyst has surpassed most metal triflates in dispensing when dried at high temperature under vacuum before use. [ABSTRACT FROM AUTHOR]

Two new tritylation reagents [viz. p-methoxybenzyl trityl ether (p-MBTE) and prenyl trityl ether (PTE)] were prepared. These two new reagents were utilized efficiently for the tritylation of alcohols, using DDQ or 20 mol% DDQ-3 eq. Mn(OAc)3. [ABSTRACT FROM AUTHOR]

One‐pot Wittig reactions of ethyl bromoacetate and bromoacetonitrile with aldehydes in the presence of PPh3 and LiOH in water were investigated. Most of the olefination reactions completed within 5–120 min in refluxing water containing 1.2 M LiCl to afford the olefin products in 71–97% yields with 100:0–55:45 ratios of E:Z isomers. [ABSTRACT FROM AUTHOR]

Various aldehydes undergo enantioselective silylcyanation with (CH3)3SiCN trimethylsilylcyanation (TMSCN) employing chiral Mn(salen) and achiral POPh3 as the catalysts. This is the double activation where Mn(salen) plays the role of Lewis acid and POPh3 Lewis base. Numerous aldehydes are subject to the enantioselective addition of TMSCN at 0°C. Hydrolysis of the adduct gave cyanohydrin with up to 96% yield and 62% ee. [ABSTRACT FROM AUTHOR]

A rapid and facile one-pot synthesis of nitriles has been carried out from the corresponding aldehydes and hydroxylamine hydrochloride in the presence of environmentally benign silica gel (84–95%), Mont K-10 (85–96%), and Mont KSF clay (88–98%) catalysts in dry media under microwave irradiation. [ABSTRACT FROM AUTHOR]

The acylation of a variety of aromatic compounds with benzoyl chloride or its derivatives and catalytic amounts of Al2O3–ZrO2/S2O82− solid superacid affords the corresponding diaryl ketones in good to excellent yields 75–93% at appropriate temperature. [ABSTRACT FROM AUTHOR]

Ferrocene and 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene undergo efficient acylation by acyl trifluoroacetates (prepared in situ from carboxylic acids and trifluoroacetic anhydride) in the presence of an excess of trifluoromethanesulfonic acid or catalytic amounts (10% mol.) of its ytterbium or hafnium salts. [ABSTRACT FROM AUTHOR]

A synthesis of the antihipertensive amide 1, named captopril, is described. The strategy is based on a Baylis–Hillman reaction between N-acryloylproline and formaldehyde. Subsequential diastereoselective hydrogenation step and functional group interconversion provided captopril in good overall yield. [ABSTRACT FROM AUTHOR]

A series of five N-[1-aryl-3-oxo-4,4,4-trifluoro-1-buten-1-yl]-o-phenylenediamines 2 [CF3COCH=C(R)NH-o-PhNH2], where R=Ph, 4-MePh, 4-BrPh, 4-ClPh, 4-OMePh from the reaction of β-aryl-β-methoxyvinyl trifluoromethyl ketones 1 with o-phenylenediamine was prepared and isolated in good yield (59–71%). Another series of five 4-aryl-2-trifluoromethyl-3H-1,5-benzodiazepines 3, where aryl=Ph, 4-MePh, 4-BrPh, 4-ClPh, 4-OMePh was also obtained in an one-step reaction from ketones 1 by an intramolecular cyclization reaction with o-phenylenediamine under mild acid conditions in good yields (60–77%). [ABSTRACT FROM AUTHOR]

Palladium-catalyzed coupling reaction of diaryliodonium salts with O,O-dialkyl phosphites gave arylphosphonates in good yields. [ABSTRACT FROM AUTHOR]

A new chiral Schiff base 4 was synthesized, which was found to be efficient catalyst for the enantioselective silylcyanation of aldehydes. The enantioselectivities of 25.1–72.7% were obtained by using the chiral Schiff base-Ti(OiPr)4 complex. [ABSTRACT FROM AUTHOR]

A convenient method for the synthesis of a series of 4-trichloromethyl-pyrimidin-2-ylamines from the reaction of 4-trichloromethyl-2-chloropyrimidine and ammonium hydroxide, primary- and secondary-amines, and guanidine hydrochloride, is reported. This reactions was also extended to obtain 4-trichloromethyl-2-alkoxy-pyrimidines. [ABSTRACT FROM AUTHOR]