Methyl formyl acetate

Based on our experiences with the NHC-catalyzed synthesis of dihydropyra-nones, we thought it conceivable that ot,p-unsaturated enol ester 51a could be converted to the iridoid cyclopenta[c]pyran core (i.e., 52a) (Scheme 11). In turn, it was envisaged that the required unsaturated enol ester 51a could be prepared via acylation of methyl formyl acetate (53a) with enantioenriched acyl chloride 54. The NHC-catalyzed rearrangement would only prove viable if it proceeded with chemoselectivity, due to the presence of additional ester functionality in enol ester 51a, and stereoselectively, to provide the correct diastereomer of 52a for the natural product. Although it was unclear whether these selectivities could be achieved, or whether the reaction would proceed with substrates annulated about the a,p-unsaturation, it was envisaged that this study would, at the very least, allow the limitations of the NHC catalysis to be examined. From the iridoid core 52a, completion of the total synthesis would require the chemo- and stereoselective reduction of the lactone to the lactol, followed by glycosylation. 

Having streamlined the synthesis of acyl chloride 54, the indirect preparation of methyl enol ester 51a was addressed. As previously discussed, attempts to synthesize 53a from formyl Meldrum s acid 58 had proven unsuccessful. However, Cossy and coworkers have reported the preparation of 53a via the ozonolysis of alkene 82 and subsequent use of the crude aldehyde in the total synthesis of octalactin. Thus, methyl vinyl acetate (82) was subjected to ozonolysis at —78 °C, followed by a reductive quench to provide formyl acetate 53a (Scheme 24). The crude methyl formyl acetate was acylated with acyl chloride 54, using the previously optimized conditions, to afford methyl enol ester 51a in 74% yield over two steps. This modification to the synthesis removes a further two reactions from the sequence with a formal synthesis of (—)-7-deoxyloganin (24) now achieved in 10 steps, a length more in keeping with the complexity of this target. 

Methyl diformyl acetate can be prepared from ketene and trimethyl orthoformate, or methyl propiolate and methanol,4 via formylation of the... 

Methyl diformyl acetate 2-Propenoic acid, 2-formyl-3-hydroxy-, methyl ester (9) (39947-70-1)... 

To a stirred mixture of the above amine hydrochloride (55.0 g, 0.22 mole) and [[(2,4-dioxo-l-imidazolidinyl)imino]methyl]formyl chloride (42.0 g, 0.22 mole) was added a solution of 440 ml of dimethylformamide and 44 ml of pyridine. The mixture was stirred for 20 h and poured into 2 L of water. The solid was collected by filtration and washed with ethanol and ether to give 36.0 g (28%) of N-[2-(4-bromophenyl)-2-oxoethyl]-[[(2,4-dioxo-l-imidazolidinyl)-imino]methyl]formamide, melting point 267°-269°C (recrystallization from 2200 ml acetic acid). 

SYNS ACETALDEHYDE DIMETHYL ACETAL 1,1-DIMETHOXYETHANE pOT) DLMETHYL ALDEHYDE ETHYLIDENE DIMETHYL ETHER METHYL FORMYL... 

Beilstein Handbook Reference) Acetaldehyde dimethyl acetal Acetaldehyde methyl acetal AI3-24137 BRN 1697039 1,1-Dimethoxyethane Dimethyl acetal Dimethyl aldehyde EINECS 208-589-8 Ethane, 1,1-dimethoxy- Ethylidene dimethyl ether FEMA No. 3426 HSDB 5427 Methyl formyl UN2377. Liquid mp = -113.2° bp = 64.5° d O = 0.8501 Xm = 290 nm soluble in... 

Methyl diformyl acetate can be prepared from ketene and trimethyl orthoformate, or methyl proplolate and methanol, via formylation of the methyl 3,3-diraethoxypropanoate intermediate (eq. 1). The present procedure is better because it avoids the tedious preparation of ketene, affords a superior yield, or is much cheaper than the other two methods. A fourth method for its preparation (eq. 2) should permit the preparation of any ester of diformylacetic acid that is stable to Birch reduction and ozonolysis conditions. However, this method is not convenient for use above a 0.1-mole scale, nor recommended for reasons of safety because of the amount of an O2/O3 mixture needed at larger scales. 

Anilino vinyl derivatives of thiazolium (30, R = H) or acetanilido (30, R = C0CH3), as well as formyl methylene 30b (methods E-G), give asymmetrical dyes when condensed with a methyl reactive group of another species (Scheme 42). Mesosubstituted symmetrical or unsymmet-rical thiazolocyanines are obtainable via /S-alkylmercaptovinyl thiazolium derivatives (32) (methods H and I) (Scheme 43). a or /S carbon atoms of the trimethine chain can be substituted by acetyl when a dye is treated with acetic anhydride (method L). The hydrolysis of neocyanines lead to trimethine cyanine by fractional elimination of a composant chain (method K). 

An early attempt to hydroformylate butenediol using a cobalt carbonyl catalyst gave tetrahydro-2-furanmethanol (95), presumably by aHybc rearrangement to 3-butene-l,2-diol before hydroformylation. Later, hydroformylation of butenediol diacetate with a rhodium complex as catalyst gave the acetate of 3-formyl-3-buten-l-ol (96). Hydrogenation in such a system gave 2-methyl-1,4-butanediol (97). 

Isomer separation beyond physical fractional crystallization has been accompHshed by derivatization using methyl formate to make /V-formyl derivatives and acetic anhydride to prepare the corresponding acetamides (1). Alkaline hydrolysis regenerates the analytically pure amine configurational isomers. 

Vilsmeier-Haack formylation of 2-(4-methyl-l-piperazinyl)-4//-pyrido-[l,2-n]pyrimidin-4-one with a mixture of POCI3 and DMF at 95°C gave a 3-formyl derivative (93FES1225) while ethyl 4-oxo-6,7,8, 9-tetrahydro-4//-pyrido[l,2-n]pyrimidine-2-acetate at 50 °C yielded a 9-dimethylaminomethylene-3-formyl derivative (01MI4). 3-Formyl-2-hydroxy-8-[2-(4-isopropyl-l,3-thiazol-2-yl)-l-ethenyl]-4//-pyrido[l,2-n]pyri-midin-4-one was obtained from the 3-unsubstituted derivative with oxalyl chloride-DMF reagent in CH2CI2 at room temperature for 3h (OlMIPl). 

Into a mixture of 1.6 g of 2-amino-4-methylpyrlmidine with 10 ml of glacial acetic acid is slowly added 2.13 g of concentrated sulfuric acid. A mixture of 2.4 g of 2-formyl-1-methyl-5-nitroimidazole in 20 ml of glacial acetic acid is slowly added to the mixture of the pyrimidine under stirring. The reaction mixture is maintained at a temperature of about 55°C for 4 hours. The resultant mixture is then diluted with 200 ml of distilled water and neutralized with a saturated aqueous solution of sodium bicarbonate. A brownish-yellow precipitate (MP 232° to 235°C) is formed and recovered. The product is analyzed by infrared spectroscopy and is found to conform to 2-amino-4-[2-(1-methyl-5-nitro-2-imidazolyI)vinyl] pyrimidine. 

To 13 of ethyl acetate were added 85.1 g (2.59 mols) of 7-emino-3-(1 -methyl-1H-tetrazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid and 1,361 g (10.37 mols) of monotrimethylsilyl acetamide, and the mixture was stirred at 50°C until a clear solution was obtained. The solution was cooled to 20°C and 514 g (2.59 mols) of 0-formyl mandeloyl chloride was added at a rate such that the temperature of the reaction solution was maintained between about 20°C to 25°C with ice-cooling. 

Pr)4, " borohydride-exchange resin,and formic acid. When the last is used, the process is called the Wallach reaction. Conjugated aldehydes are converted to alkenyl-amines with the amine/silica gel followed by reduction with zinc borohydride.In the particular case where primary or secondary amines are reductively methylated with formaldehyde and formic acid, the method is called the Esch-weiler-Clarke procedure. It is possible to use ammonium (or amine) salts of formic acid, " or formamides, as a substitute for the Wallach conditions. This method is called the Leuckart reaction,and in this case the products obtained are often the N-formyl derivatives of the amines instead of the free amines. Primary and secondary amines can be iV-ethylated (e.g., ArNHR ArNREt) by treatment with NaBH4 in acetic acid. Aldehydes react with aniline in the presence of Mont-morillonite KIO clay and microwaves to give the amine. Formaldehyde with formic acid converts secondary amines to the N-methyl derivative with microwave irradiation. 

Spirothiopyrans 45b including a benzopyrylium ring have been prepared in one step by condensation of 2-aminovinyl-3-formyl chromone-4-thione 47 with 1,2,3,3-tetramethylindolinium salts in ethanol (Scheme 25).90 The precursor 47 is prepared from 3-carboxymethylene-2-methyl-chromone-4-thione 48. First, oxidation of 48 with pyridinium dichromate in CH2C12, and then condensation with dimethyl formamide dimethyl acetal in benzene gave compound 47. 

Other Methods of Preparation.—Ethyl 2-formyl-5-methyl-4-furoate has also been prepared by the oxidation of ethyl 2-(D-ara6ino-tetrahydroxybutyl)-5-methyl-4-furoate by means of periodic acid,8 sodium periodate,19 or minium ( red lead ) in acetic acid.66 It can also be prepared by the oxidation with sodium periodate of ethyl 2-(D-lyzo-tetrahydroxybutyl)-5-methyl-4-furoate,15 of ethyl 2-(D-fftreo-trihydroxy-propyl)-5-methyl-4-furoate,13 of ethyl 2-(o-erythro-trihydroxypropyl)-5-methyl-4-furoate,17 of ethyl 2-(L-eryfAro-trihydroxypropyl)-5-methyl-4-furoate,13 and of ethyl 2-(D-goIado-pentahydroxypentyl)-5-methyl-4-furoate.16... 

To 21.6 g phenylhydrazine dissolved in 300 ml 0.3N sulfuric acid, add 9.8 g concentrated sulfuric acid. Add dropwise with stirring and heating at 100°, 11.6 g methyl-beta-formyl-propionate in 300 ml 0.3 N sulfuric acid and continue heating six hours to get 14 g indole-3-acetic acid. Convert to the dialkyltryptamine as already described. 

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