Tiemann Reaction Research Articles

Zeolites as Shape-Selective Catalysts: Highly Selective Synthesis of Vanillin from Reimer–Tiemann Reaction of Guaiacol and Chloroform

Reimer–Tiemann reaction of guaiacol and chloroform was carried out in the presence of various zeolites. Vanillin was afforded as major product in a high selectivity. Zeolites played an important role of shape-selective catalysts in the reactions. Among the examined zeolites, ZSM-5 showed the best result to give the desired product vanillin in 85 % selectivity and 58 % yield.

Derivatization of Coumarins at the Benzenoid Ring in Aqueous Medium

Some 6‐disubstituted, 8‐disubstituted, and/6,8‐disubstituted compounds have been prepared from coumarin, 7‐methylcoumarin, and 3,4‐benzocoumarin. The Reimer–Tiemann reaction, Lederer–Manasse reaction, bromination using molecular bromine as well as 2,4,4,6‐tetrabromocyclohex‐2,5‐dien‐1‐one, Elbs reaction, and diazocoupling have been carried under controlled conditions to obtain various derivatives. Further, several reactions of aldehyde derivatives of these coumarins have been carried on to prepare important functional compounds including some heterocycles. It is noteworthy that these aldehydes behave as phenolic aldehydes under alkaline conditions to undergo the Dakin reaction. The reactions are mostly carried in aqueous media involving a dianionic intermediate and hence fulfill one important criterion of green chemistry.

Organometallic Sn(II) catalyzing adducts of substituted benzaldehydes

This paper reports about the electrospray ionization mass spectrometric and quantum chemical study of unique coupling reaction of dihydroxybenzaldehydes in strong basic medium, which in the presence of SnIVCl4 yielded series of condensation products through the homo Dies-Alder reaction of the bicyclohexyl-4,6,4′,6′-tetraene-2,3,2′,3′-tetraone (2). In contrast to the known coupling reaction products catalyzing by diversity of CuI/CuII-, AgI-, Au0/AuIII/AuI-, ZnII-, Pd0/PdIII/PdII- and/or PtII-organometallics, yielding the substituted biphenyls, benzo-[c]-cromenes, condensation products of 5,6,11,12-tetraoxo-tricyclo[6.2.2.02,7]dodeca-3,9-diene-1,4-dicarbaldehyde (14) type from 2,3-dihydroxybenzaldehyde particularly, and/or substituted aldehydes by Reimer–Tiemann reaction, in the presence of SnIVCl4, the formation of above dimeric adducts is chiefly process, explained with SnIV→SnII redox process. The known product 14 is obtained at trace concentrations, producing further dimeric 5,6,11,12,5′,6′,11′,12′-octaoxo-[4,4′]bi[tricyclo[6.2.2.02,7]dodecyl]-3,9,3′,9′-tetraene-1,1′-dicarbaldehyde adduct (15). The catalyzing organometallic precursor is a binuclear SnII-complex (I), where the metal ion is bonded covalently in ClSnC manner. A second metal ion is bidentately coordinated to adjacent OC groups, forming a five membered chelate ring. The Cl− and OH−-terminal ligands completed the SnO3Cl chromophore. The experimentally evidenced complex I exhibited a significant thermodynamics stability of ΔG=−52996.80kcalmol−1, a value different than Δ(ΔG)=|52945| kcalmol−1 towards the corresponding quantities of other structurally proposed analogous of SnII, SnIV or SnII/SnIV organometallics II–IV on the base of the MS elemental compositions and isotopic shapes.

ChemInform Abstract: Reimer—Tiemann Reaction of Coumarins.

AbstractImproved yields of aldehydes (III) are achieved when the Reimer—Tiemann reaction is carried out as a 2‐step process.

Reimer–Tiemann Reaction of Coumarins

Improved yields of aldehydes from the Reimer–Tiemann reaction of coumarin and two of its derivatives, namely 7-methylcoumarin and 3,4-benzocoumarin, are obtained by carrying the reaction in a two-step procedure. Using crown ether as phase transfer catalyst, a further improvement in the yield of products is achieved. Additionally, coumarin and 7-methylcoumarin are shown to give dialdehydes under this condition. Dialdehydes are reported for the first time from the Reimer–Tiemann reaction.

ChemInform Abstract: Mild, Simple, and Efficient Method for N‐Formylation of Secondary Amines via Reimer—Tiemann Reaction.

Abstract A rapid and easy route for the N-formylation of secondary amines using chloroform and sodium ethoxide via dichlorocarbene by the Riemer–Tiemann reaction with excellent yield is reported.

Mild, Simple, and Efficient Method for N-Formylation of Secondary Amines via Reimer–Tiemann Reaction

A rapid and easy route for the N-formylation of secondary amines using chloroform and sodium ethoxide via dichlorocarbene by the Riemer–Tiemann reaction with excellent yield is reported.

A significant role of alkaline cations on the Reimer–Tiemann reaction

The Reimer-Tiemann (R-T) reaction was investigated by DFT calculations. A model composed of CHCl(3), PhO(-)(Na(+))H(2)O and [NaOH(H(2)O)(2)](2) was employed for geometry optimizations. A K(+)-containing model was also investigated. The dichlorocarbene reagent, which has been thought of for a long time, was found to intervene only transiently in the carbenoid form. In this form, the Na(+) (or K(+)) coordination to CCl(2) enhances its electrophilicity toward C(6)H(5)O(-). The counter ion also works to stabilize the precursor phenoxide ion and intermediates of the substituted phenoxides in the hexagonal pyramidal coordination. The Na(+)-containing reaction consists of seven elementary processes, (K(+), six ones) with extremely high exothermicity and spontaneity.

α-Glucosidase inhibitory antihyperglycemic activity of substituted chromenone derivatives

Series of 3,4- and 3,6-disubstituted chromenones including new chromenone derivatives were synthesized applying various synthetic strategies including Pechmann condensation, Knoevenagel condensation, Reimer–Tiemann reaction and Suzuki coupling in very good yields. Synthesized compounds ( 4a– z) were screened for in vitro α-glucosidase inhibitory and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities. Majority of compounds displayed varying degrees of α-glucosidase inhibitory and DPPH scavenging activity. Compound 4x emerged as the most potent α-glucosidase inhibitor in present series of compounds owing to the presence of 3-acetyl-6-(6-methoxy-3-pyridyl) group on chromenone; however, it could not display DPPH scavenging activity and was found to be mixed non-competitive type inhibitor of rat intestinal α-glucosidase. When tested in vivo for antihyperglycemic activity in starch loaded Wistar rats, it displayed significant antihyperglycemic property. This is the first report assigning rat intestinal α-glucosidase inhibitory property for this class of new chromenones and presents new family of compounds possessing α-glucosidase inhibitory activities and antihyperglycemic property. Compound 4x may serve as an interesting new compound for the development of therapeutics targeted against diet-induced hyperglycemia in diabetes.

Synthesis of Substituted 2‐Hydroxyaryl Aldehydes by the Microwave‐Induced Reimer—Tiemann 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.

Synthesis of Novel Photochromic 6‐Benzyloxo‐spirobenzopyran Compounds.

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 Improved Procedure for the Synthesis of 2-Hydroxybenzaldehyde and 2-Hydroxynaphthalene-1-Carbaldehyde

An easy and convenient method is reported for the synthesis of 2-hydroxybenzaldehyde and 2-hydroxynaphthalene-1-carbaldehyde from corresponding phenols by Reimer–Tiemann reaction using aqueous ethyl alcohol and avoiding steam/vaccum distillation.

Synthesis of Novel Photochromic 6‐Benzyloxo‐spirobenzopyran Compounds

The synthesis of four novel derivatives of 1′,3′,3′‐trimethylspiro‐[2H‐1]‐benzopyran‐6‐benzyloxo‐2,2′‐indoline is reported. The synthetic approach to these compounds involves the preparation of the key compound, 3‐formyl‐4‐hydroxybenzophenone, by means of the Reimer–Tiemann reaction. The photochromic compounds were isolated and characterized by 1H and 13C NMR as well as FT‐IR and UV‐VIS spectrometry. Comparative studies performed in these compounds showed a higher molar extinction coefficient and red shift of maximum absorption wavelength when the benzyloxo group is introduced in the spirobenzopyran molecule.

Photochemistry of Phenols

AbstractFor Abstract see ChemInform Abstract in Full Text.

Thermal optimisation of the Reimer–Tiemann reaction using thermochromic liquid crystals on a microfluidic reactor

Microreactors incorporating thin film resistive heating elements for continuous flow organic synthesis are presented. Internal thermal conditions were monitored in real time using reflectance spectra of temperature sensitive thermochromic liquid crystals (TLC) in a collateral microfluidic network. To demonstrate the precise temperature control provided by this method, the thermal optimisation of the Reimer-Tiemann formylation of beta-naphthol was performed under hydrodynamic pumping regimes.

A general approach to l-tyrosine porphyrins

A novel and general approach has been developed to prepare l-tyrosine-containing porphyrins. The key intermediates, 2- tert-butoxycarbonylamino-3-(3-formyl-4-hexyloxy-phenyl)-propionic acid hexyl ester and 2- tert-butoxycarbonylamino-3-(3-formyl-4-methoxy-phenyl)-propionic acid methyl ester, were prepared by the Reimer–Tiemann reaction of Boc-protected l-tyrosine, which was followed by esterification and alkylation of the phenol hydroxide. A number of novel chiral l-tyrosine porphyrins were obtained from the reactions of 2- tert-butoxycarbonylamino-3-(3-formyl-4-alkoxy-phenyl)-propionic acid ester with different dipyrrolylmethanes and the reaction of 5-(4-trifluoromethylphenyl)pyrromethane afforded the highest yield. The tyrosine porphyrins could be readily deprotected to afford the corresponding diacid or diamine derivatives.

Regioselectivity in the preparation of 2-hydroxy-4-methoxy benzaldehyde from resorcinol

Three reactions, namely, Reimer–Tiemann reaction of resorcinol, one pot Reimer–Tiemann reaction of resorcinol and its methylation and finally Reimer–Tiemann reaction of resorcinol monomethyl ether were studied. Better selectivities were observed in the first two reactions when β-cyclodextrin (β-CD) and its derivatives were employed. The formation of 2,4-dihydroxybenzaldehyde and 2-hydroxy-4-methoxybenzaldehyde from the first two reactions showed better conversion than the control reaction. In the process, 70.0% 2,4-dihydroxybenzaldehyde was detected in the presence of 1 equivalent of β-CD and 48.2% 2-hydroxy-4-methoxybenzaldehyde was detected in the presence of 0.2 equivalent of HPβ-CD. However, Reimer–Tiemann reaction of resorcinol monomethyl ether resulted in only a marginal increase (43.9%) of 2-hydroxy-4-methoxybenzaldehyde (I) in the presence of 0.2 equivalent of β-CD as compared to the control (35.2%). The observed results were explained in terms of specific orientation of resorcinol inside the β-CD cavity which facilitates the attack of dichlorocbenzene from the narrower end on the electron rich ortho position to the OH of resorcinol leading to the formation of 2,4-dihydroxybenzaldehyde or 2-hydroxy-4-methoxybenzaldehyde(I).

A theoretical study on the molecular mechanism for the normal Reimer–Tiemann reaction

Normal Reimer–Tiemann rearrangement (reaction of pyrrole ring and dichlorocarbene in basic media to yield pyrrole-2-carboxaldehyde) has been theoretically characterized at HF/6-311++G ∗∗, MP2//6-31++G ∗∗ and B3LYP//6-31++G ∗∗ computing levels. Analysis of the results shows that the molecular mechanism comprises six steps; the first is a barrierless process associated with the addition of dichlorocarbene on the α position of pyrrole anion; the second and rate-limiting step corresponds with an intramolecular hydrogen transfer from the α carbon of the pyrrole ring to the carbon atom of the incoming dichlorocarbene fragment; the subsequent pathways are a nucleophilic substitution of Cl − by OH − on this carbon atom along an uncharged intermediate, followed by a Cl − leaving process and finally the product, pyrrole-2-carboxaldehyde, is obtained along an intramolecular hydrogen transfer from the hydroxyl group to the nitrogen atom of the ring. Solvent effects of the ether medium on the rate-limiting step are analyzed by using a polarizable continuum model.

Theoretical investigation of the abnormal Reimer–Tiemann reaction

Theoretical investigation of the abnormal Reimer–Tiemann reaction

β-Cyclodextrin mediated regioselective photo-Reimer–Tiemann reaction of phenols

In the presence of β-cyclodextrin and its derivatives, the photo-Reimer–Tiemann reaction of phenols with chloroform proceeded smoothly with high selectivity for the formation of 4-hydroxy benzaldehydes.