Expedient synthesis of 1-vinylpyrrole-2-carbaldehydes

1-Vinylpyrrole-2-carbaldehydes and 1-vinyl-4,5-dihydrobenzo[g]indole-2-carbaldehyde were synthesized in 56-91% yields from their 1-vinyl derivatives by a modified Vilsmeier-Haack reaction. A low temperature (−78 °C) is required to avoid removal of the N-vinyl group, whereas at elevated temperature (reflux in 1,2-dichloroethane) the latter process leads to direct conversion of 1-vinylpyrroles to pyrrole-2-carbaldehydes.     

Differentiating alkyne reactivity in the post-Ugi transformations: Access to polycyclic indole-fused frameworks

The Ugi adducts prepared from propiolic acids, propargylamines, indole-2-carbaldehydes, and isocyanides were utilized to assemble polycyclic indole-fused frameworks via two consecutive carbocyclizations involving triple bonds. First, the peptidyl position of Ugi adduct underwent potassium carbonate-mediated cyclization onto the triple bond derived from propiolic acid. Then, the position 3 of indole core engaged into gold-catalyzed cyclization onto the propargylamine-originated alkyne, completing the construction of polycyclic core.     

Microwave-Assisted Synthesis of Some Indole and Isoniazid Derivatives as Antitubercular Agents and Molecular Docking Study

Russian Journal of Organic Chemistry - An efficient and expeditious microwave-assisted synthesis of isoniazid derivatives from various indole-3-carbaldehydes, phenols, and isoniazid via...     

Synthesis of Tri-indolylmethane Derivatives Using a Deep Eutectic Solvent

Russian Journal of Organic Chemistry - An efficient and facile synthesis of tri-indolylmethane derivatives in a deep eutectic solvent, starting from indoles and indole-3-carbaldehydes, is...     

Domino Vilsmeier-Haack/ring closure sequences: a facile synthesis of 3-chlorobenzo[b]thiophene-2-carbaldehydes

Vilsmeier’s reagent treatment of substituted diphenacyl sulfides or diphenacyl disulfides has led to the formation of a series of benzfused 3-chlorothiophene-2-carbaldehydes by a Domino Vilsmeier-Haack reaction/ring closure sequence, opening a new route for the synthesis of 3-chlorobenzo[b]thiophene-2-carbaldehydes and their benzfused analogues. A plausible mechanism has been proposed.     

2-Amidinylindole-3-carbaldehydes: synthesis of new tetracyclic compounds containing the pyrrolo[1,2-c]1,4-diazepine ring

2-Amidinylindol-3-carbaldehydes bearing an α-alkoxycarbonyl substituent on the cyclic-tertiary amine moiety were prepared. Pyrolysis of these amidines in diethylenglycol-monoethyl ether produced mainly a pyrrolo[1′,2′-1,2]-1,4-diazepino[5,6-b]indol-7,11-dione. A similar result was obtained starting from 2-amidinylbenzofuran-3-carbaldehyde.     

Metal-free synthesis of benzimidazo[2,1-a]ellipticines via tandem inter and intramolecular cyclization

Synthesis of the new benzimidazo[2,1-a]ellipticine derivatives via tandem inter and intramolecular, 5-endo,6-endo cyclization of various 9-ethyl-2-(alkynyl)carbazole-3-carbaldehydes with different 1,2-aryldiamines is reported under metal free condition in good yields.     

2-羟基脱氧雌酚酮的合成

2-羟基雌甾化合物是人体内对生理机能有重要意义的雌激素代谢产物,其在生物体内的含量极少,需用化学方法合成来满足研究、应用的需要。迄今为止,已报道了较多合成2-羟基和4-羟基雌甾化合物的方法[1-3],但选择性和产率并不十分理想。我们在文献报道的合成路线[1]的基础上,合成了     

Domino addition/annulation of δ-alkynylaldehydes and oxygen nucleophiles: a new entry to [1,4]oxazino[4,3-a]indoles

The unusual [1,4]oxazino[4,3-a]indole nucleus was prepared, under mild reaction conditions, by reacting 1-alkynyl-1H-indole-2-carbaldehydes with various alkoxides, generated in situ from the corresponding alkyl, benzyl, allyl and propargyl alcohols.     

Base- and light-assisted synthesis of anthracenes from 3-allylnaphthalene-2-carbaldehydes

The synthesis of substituted anthracenes from naphthalene precursors is described. The key step involved heating ortho-allyl substituted naphthalene-2-carbaldehydes and potassium t-butoxide in DMF with concomitant irradiation from a high pressure mercury lamp to afford anthracenes in yields of 76-98%.     

N-Alkylhydrazones of aliphatic ketones in the synthesis of 1,3,4-trisubstituted non-symmetric pyrazoles

Reactions of N-alkylhydrazones of aliphatic ketones with the Vilsmeier–Haack reagent (DMF–POCl₃) were evaluated as a promising approach toward the synthesis of trisubstituted non-symmetric pyrazoles. It was found that either 1,3,4-trialkylpyrazoles or 1,3-dialkylpyrazole-4-carbaldehydes could be obtained in these transformations in high yields (72–83%), in a regioselective manner.     

A mild oxidation of deactivated naphthalenes and anthracenes to corresponding para-quinones by N-bromosuccinimide

A new method to synthesize 1,4-naphthoquinone and 9,10-anthraquinone from naphthalene and anthracene functionalized with either –CHO or –COOH groups, using N-bromosuccinimide (NBS) in aqueous N,N-dimethylformamide at 75–80 °C, has been developed. Further, –CN and –CONH₂ functionalized naphthalenes and anthracenes can also be transformed into respective para-quinones in a one pot reaction, after successive acid hydrolysis and subsequent reaction with NBS. We believe that the present finding may serve as a valuable alternative to the classical approaches for the synthesis of polycyclic quinones from polyaromatic carbaldehydes through Dakin oxidation followed by further oxidation of the resulting hydroquinone by heavy metal oxides.     

First construction of 12H-thiochromeno[2,3-b]quinolines and 5H-benzo[7,8]thiocino-[2,3-b]quinolines via intramolecular Friedel-Crafts reaction of Morita-Baylis-Hillman adducts

An acid-promoted intramolecular Friedel-Crafts reaction of the Morita-Baylis-Hillman adducts 3 derived from 2-arylthioquinolin-3-carbaldehydes 2 was investigated. Interestingly, promoted by sulfuric acid, the substrates with electron-donating groups on the aromatic ring gave six-membered fused-ring 12H-thiochromeno[2,3-b]quinolines 4 with good yields, while those with electron-withdrawing groups afforded eight-membered fused-ring 5H-benzo[7,8]thiocino[2,3-b]quinolines 5 in moderate yields. Using triflic acid instead of sulfuric acid, only products 4 could be obtained under the similar condition.     

Formation of tryptanthrin compounds upon Oxone-induced dimerization of indole-3-carbaldehydes

Tryptanthrin is a natural product with numerous important pharmacological properties. Tryptanthrin and its analogs are commonly prepared by condensation of isatoic anhydride and isatin. In this Letter we investigate the formation of tryptanthrin derivatives upon Oxone-induced oxidative dimerization of indole-3-carbaldehydes.     

Regioselective formylation of pyrazolo[3,4-b]pyridine and pyrazolo[1,5-a]pyrimidine systems using Vilsmeier-Haack conditions

Regioselective formylation behavior has been found in the reaction of pyrazolo[3,4-b]pyridines and pyrazolo[1,5-a]pyrimidines via Vilsmeier-Haack conditions. While the 4,5- and 6,7-dihydro derivatives afforded pyrazolo[3,4-b]pyridine-5-carbaldehydes and 4,7-dihydropyrazolo[1,5-a]pyrimidine-3,6-dicarbaldehydes, respectively, the aromatic analogs rendered the pyrazolo[1,5-a]pyrimidine-3-carbaldehyde only, and no reaction took place at the pyrazolopyridine derivatives.     

Efficient synthesis of novel functionalized pyrazolo-pyranoquinoline and tetrahydrodibenzo-[1,8]naphthyridinone derivatives

The facile and efficient synthesis of 1,4-dihydropyrazolo-pyrano-[2,3-b]quinoline derivatives from the reaction of 2-chloroquinoline-3-carbaldehydes and pyrazolones is described. Moreover, a one-pot method for the development of functionalized tetrahydrodibenzo[b,g][1,8]naphthyridinone derivatives is reported by using a three-component reaction of 2-chloroquinoline 3-carbaldehydes, pyrazolone, and enaminones catalyzed by l-proline in EtOH.     

Reaction of 1,2,3,4-Tetrahydropyrimido[1,2-a]indol-10-ylmethyleniminium salts with certain nucleophilic agent

Summary The reaction of iminium salts of 1,2,3,4-tetrahydropyrimido[1,2-a]indole-10-carbaldehydes with sodium hydrosulfide, amines, formation of the corresponding and thioaldehydes, azomethines, and nitrovinyl derivatives, existing predominantly in the enamidine form.M. V. Lomonosov Moscow State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii No. 3. pp. 381–387. March, 1995. Original article submitted February 8, 1995     

Convenient synthesis and unusual reactivity of 2-oxo-2H,5H-pyrano[3,2-c]chromenes

The reaction of 4-oxo-4H-chromen-3-carbaldehydes with coumarin-4-acetic acids under the Perkin conditions follows an interesting pathway that involves aldol reaction and subsequent intramolecular lactonization to afford 2-oxo-2H,5H-pyrano[3,2-c]chromene skeleton. In contrast to chromone-3-carbaldehydes, the same reaction with chromone-2-carbaldehydes yielded only the aldol condensation product. The reaction was performed under thermal and microwave conditions. The reactivity of 2-oxo-2H,5H-pyrano[3,2-c]chromenes in water, alcohol and acetic acid was described.     

Tandem reactions of 6-phenylethynylpyrimidine-5-carbaldehydes with alcohols: regioselective synthesis of 5-alkoxy-(7Z)-7-benzylidene-5,7-dihydrofuro[3,4-d]pyrimidines and 5-alkoxy-7-phenyl-5H-pyrano[4,3-d]pyrimidines

An efficient and versatile tandem processes of acetalisation and cycloisomerization reactions have been developed for the reactions of 6-phenylethynylpyrimidine-5-carbaldehydes. The influence of the catalyst and role of the substituent in the position 4 of the pyrimidine ring have been studied. Regioselective synthesis of 5,7-dihydrofuro[3,4-d]pyrimidine and pyrano[4,3-d]pyrimidine cores is described.     

Preparation of 6-chloropyrazolo[3,4-b]pyridine-5-carbaldehydes by Vilsmeier-Haack reaction and its use in the synthesis of heterocyclic chalcones and dipyrazolopyridines

Novel 6-chloropyrazolo[3,4-b]pyridine-5-carbaldehydes 5 have been synthesized from the 4,5-dihydropyrazolo[3,4-b]pyridine-6-ones 4 via Vilsmeier-Haack reaction. Further treatment of carbaldehydes 5 with acetophenones 6 and hydrazine hydrate afforded chalcone analogues 7 and dipyrazolo[3,4-b:4′,3′-e]pyridines 8, respectively.