Treatment with DMF

Demethylation of toxoflavins (941) to reumycin (942) is effected by dimethylformamide or diethylamine and also proceeds via radical-anions (87JHC1373). On treatment with DMF and methyl iodide, (941, R=H) undergoes a concomitant demethylation and methylation to give the fervenulin (943) (74JHC271, 75BCJ2884). 

Ring opening of phthalanes 614 to form the bis-lithiated species 615 via reductive lithiation, followed by treatment with DMF furnishes anomeric 3-hydroxy-4-arylisochromans 616. The mixture of anomers obtained can be converted to a -3-carboxymethyl-4-aryl isochromans 617 using Mukaiyama s procedure (Scheme 132) <2001TL9293>. Similar bis-lithiated species can react with (—)-menthone, with the subsequent dehydration leading to C(3)-spiro-cyclic isochromans <2004S 1115>. 

Metallation of furo[3,2-c]pyridines with t-butyllithium followed by treatment with DMF or DMA (dimethylacetamide) generated fair yields of the 2-carboxy derivatives. Data are summarized in Table 44 <83T1777>. 

Vilsmeier formylation of the thienylpyrroles 49 gives only the pyrrole-formylated products (Equation 14) <2006T3493>. The formyl group could be introduced on the thiophene ring by lithiation and subsequent treatment with DMF. 

Regioselective lithiations have also been utilized to prepare other benzene-ring functionalized indoles. For example, the selective halogen-metal exchange of 4,7-dibromoindole 152 led to the formation of 7-lithioindole intermediate 153, which in turn gave indole-7-carboxaldehyde 154 upon treatment with DMF <03TL5987>. 

Phenols and primary alcohols form ethers when heated with dicyclohexylcarbo-diimide " (see 16-63). 1,2-Diols can be converted to epoxides by treatment with DMF dimethyl acetal, (MeO)2CHNMe2, with diethyl azodicarboxylate, EtOOCN=NCOOEt, and Ph3P, with a dialkoxytriphenylphosphorane, or with TsCrNa OHPhCH2NEtJ Cr. ... 

Sulfonyl halides (e.g. benzenesulfonyl chloride) form adducts (11) with acid amides in an equilibrium reaction. From these adducts or via adducts of this type 0-sulfonated lactim ethers, isonitriles, adenine, nitriles, amidines, amidinium salts and formic acid esters were prepared. The adducts from DMF and chlorosulfonamides (12) can be used to prepare amidines or amidrazones. A/-Chlorosulfonylcarboxylic acid amides yield nitriles on treatment with DMF or other tertiary amides, presumably via an acid amide sulfonyl chloride complex (13 equation 3). ... 

CSI reacts with carboxylic acids to form nitriles via the initial adducts (75) which lose carbon dioxide to give the N-chlorosulfonylcarboxamides (76) which with DMF afford good yields of the nitriles (77) (Scheme 36). This provides a valuable procedure for the conversion of carboxylic acids into the nitriles. In addition, thiophene (78), as well as other reactive heterocycles, reacts with CSI to yield the N-chlorosulfonylcarboxamide (79) which on treatment with DMF affords the nitrile (80) (Scheme 37). 

Self-condensation of 6-aminouracils occurs on treatment with DMF and an acid (Scheme 26).34,70... 

An iterative directed-metallating approach to 4,5-substituted indoles starting from gramine was documented <05T6886>. Treatment of gramine 173 with tert-butyllithium and trimethylsilylmethylazide followed by Boc protection gave 4-aminoindole 174. Directed lithiation by the carbamate followed by treatment with DMF gave indole 175. 

To confirm its structure, Reisch et al. have synthesized hallacridone 347 (Scheme 68) [89JCS(P1)1047]. Ullmann-amine coupling of 2-chlorobenzoic acid and 3,5-dimethoxyaniline gave an amine 354 that, on treatment with DMF-POCI3, provided 4-formyl-l,3-dimethoxyacridin-9(10//)-one 355. A-Methylation, O-demethylation, and subsequent condensation with 1-chloropropan-2-one in basic media gave hallacridone 347. 

The reaction of CSI with ketones produces N-chlorosulfonyl-/ -ketocarboxamides 169, which upon treatment with DMF give / -ketonitriles 171, important intermediates for the synthesis of many heterocyclic compounds (equation 86)81. The examples are shown in Table 7. 

Electrophilic reaction of heterocycles, such as thiophene or indole, with equimolar amounts of chlorosulfonyl isocyanate in dry ether or acetonitrile at 0-5 °C produces N-chlorosulfonyl-substituted heterocycles (173), which on treatment with DMF gave nitriles in good yields (equations 90 and 91)83. 

Capping The capping solution [DMF-acetic anhydride-lutidine (89 5 6)] is added to the resin. After a 1-min treatment the capping solution is removed and the resin is washed with DMF. A 1-min treatment with DMF-piperidine (19 1) is performed to remove undesired acyl moieties. After washing with DMF and DCM, the cycle is repeated. 

Ranu et al. have developed a mild and efficient method for the synthesis of a-dehydro-p-amino esters and nitriles by nucleophilic addition of amines to MBH acetates in water at room temperature without using any basic, acidic or metal catalyst. The reactions yielded only y-addition products, providing, with high stereoselectively, ( )-isomers in the case of MBH adducts bearing a carboxylic ester moiety and (Z)-isomers for adducts containing CN functionality (Scheme 3.123). An interesting stereoselective transformation of MBH adducts into cinna-mylamines via treatment with DMF-DMA has been described by Kim and coworkers (Scheme 3.124). ... 

Fluoroquinoline (173, X=H) was obtained by reduction of 2-bromo-3-fluoroquinoline 173 (X=Br) with Pd/C and NEts in methanol. Bromo derivative 176 (R =COOH) has been shown to form the corresponding organomagnesium compound, which was transformed on treatment with DMF into aldehyde 176 [R =COOH, X=C(0)H] and its thiosemicarbazone derivative 176 [R =COOH, X=CH NNHC(S)NH2] [106], In a similar way 2-bromo-3-fluoroquinolm-4-carbaldehyde and its 1,3-dioxalan were obtained from 4-lithium-3-fluoro-2-bromoquinoline and DMF. 

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