1- Acetyl-6-methoxycarbonyl

Especially sensitive quinones can be generated in situ, the diene adduct, eg (88), can be obtained in excellent yield (87). For R = methoxycarbonyl, carboxaldehyde, and acetyl, the yields are 95, 97, and 100%, respectively. 

Methoxycarbonyl and acetyl derivatives Relative rates of decomposition into cyclopropanes and alkenes 75JCS(P2)1791... 

V,7V-dimethylaminopyridme provides l-(2-methoxycarbonyl)ethoxy- (40,69%) and l-(2-methoxycarbonyl-l-methyl)ethoxytryptamine (41, 72%), respectively (Scheme 4). The conjugate addition to mesityl oxide proceeds successfully as well, giving iVb-acetyl-1-(1, l-dimethyl-3-oxo)butoxytryptamine (42,49%), while the reaction with methyl 3-methylcrotonate affords 43 in a miserable yield (1.6%). Addition to acrolein results in failure, and 44 is not yet obtained. 

An acetyl group in the 2-position favors the monocyclic structure presumably because of the resonance stabilization.12 The same observation was made with oxepin-2,7-dicarbaldehyde, oxepin-2,7-dicarboxylic acid, and oxepin-2,7-dicarbonitrile.23 Substituents in the 4- and 5-positions of the oxepin such as methyl or methoxycarbonyl groups shift the equilibrium towards the epoxide.12 24 Low temperature 1H NMR studies on 7-ethyloxepin-2-carbonitrile and ethyl 7-ethyloxepin-2-carboxylate established a nonplanar boat geometry with a ring-inversion harrier of 6.5 kcal mol-1.25... 

Reaction of 2-cyanomethylpyridine with iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)-iV -(4-methylphenyl)carbodiimides, and with (1,1,2,2,2-pentachloro- and l,l-dichloro-2,2,2-trifluoroethyl)isocyanates or A-methoxycarbonyl-l,2,2,2-tetrachloro-, — l-chloro-2,2-trifluoroacetaldehyde imines afforded 3-aryl-4-cyano-l-(4-methylphenyl)imino-3-trifluoromethyl-2,3-dihydro-17/-pyrido[l,2-f]pyrimidines and 4-cyano-3-trichloro-, 4-cyano-3-trifluoro-17/-pyrido[l,2-4pyrimidin-l-ones, respectively <2004CHE47>. Refluxing 2-cyanomethylpyridine and iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)isocyanates in benzene furnished l-aryl-4-cyano-l-trifluoromethyl-l,2-dihydro-3//-pyrido[l,2-4pyrimidin-3-ones. However, when the solution of the isocyanate was added dropwise to the solution of 2-cyanomethylpyridine, and the reaction mixture was then treated with NEt at room temperature, the isomeric 3-aryl-4-cyano-3-trifluoromethyl-2,3-dihydro-l//-pyr-ido[l,2-dpyrimidin-l-ones were obtained. Reaction of l-(acetyl- and benzoylmethylene)-6,7-dimethoxy-l,2,3,4-tetra-hydroisoquinolines with PhCONCS yielded 1-acetyl-, 1 -benzoyl-9,10-dime thoxy-3-pheny 1-6,7-dihydro-2//-pyrimido[6,l- ]isoquinoline-2-thiones <2003SL2369>. 

When l-[diazo(methoxycarbonyl)acetyl]-2-oxopyrrolidine derivative 231 was treated with Rh2(pfm)4 (pfm = per-fluorobutyro amidate) in the presence of W-phenylmaleimide, none of the desired dipolar cycloadduct was formed but instead the acidic proton at C-3 in the isomiinchnone intermediate 232 was transferred, and the fused oxazoli-dinone 3-oxo-2,3,5,6-tetrahydropyrrolo[2,l- ]oxazole-2,7-dicarboxylic acid dimethyl ester 233 was isolated in 77% yield (Scheme 33) <1997JOC6842>. 

Under Dakin-West reaction conditions (trifluoroacetic anhydride-MeCN/80 °C/5 h), At-methoxycarbonylproline (128 R = Me) yielded Af-methoxycarbonyl-4-trifluoro-acetyl-2,3-dihydropyrrole (129 R = Me) and none of the expected Dakin-West product, the trifluoromethyl ketone (127). A possible mechanism proposed by the authors involves initial formation of a mesoionic l,3-oxazolium-5-olate (130 R = Me), but the pathway to the iV-methoxycarbonyl-2,3-dihydropyrrole (131 R = Me) and thence the final product (129 R = Me) was unexplained. ... 

The amidic group in methyl A -acetyl-p-aminobenzoate was reduced preferentially to an ester group with borane in tetrahydrofuran (1.5-1.8 mol per mol of the amide), giving 66% yield of methyl p-A -ethylaminobenzoate. Similarly l-benzyl-3-methoxycarbonyl-5-pyrrolidone afforded methyl l-ben2yl-3-pyr-rolidinecarboxylate in 54% yield and l,2-diethyl-5-ethoxycarbonyl-3-pyra-zolidone gave ethyl l,2-diethylpyrazolidine-3-carboxylate in 60% yield. 

New pyrazolo[l,5-a]pyrimidine derivatives have been synthesized. These compounds are potent angiotensin-ll receptor antagonists <99CPB928>. Pyrazolot3,4-ri]dihydropyridazinone derivatives have been obtained by the reaction of 5-methyl-4-methoxycarbonyl-3-acetyl-1-phenylpyrazole with different hydrazines <99TL3891>. A direct synthesis of pyrazolo [3,4-b]pyridines 69 from pyrazole 67 and benzothiazole 68, through a Friendlander condensation, has been described <99SC655>. 

Die C-Hetarylierung1,2 von Nitro-alkanen gelingt in hohen Ausbeuten mit substituierten 5-Acetyl-2-nitro- und 5-Methoxycarbonyl-2-nitro-furan unter Denitrierung am Furan-System in Kalium-tert.-butanolat/Phosphorsaure-tris-[dimethylamid]1 ... 

Reaction of 2,2-difluoro-2-(methoxycarbonyl)acetyl chloride (3) with potassium fluoride affords 2,2-difluoro-2-(methoxycarbonyl)acetyl fluoride (4) in 90 % yield, which is one of the precursors for the preparation of perfluorovinyl ethers containing a carboxylic group.30... 

The reactivity of five-membered rings with one heteroatom to electrophilic reagents has been quantitatively compared. Table 1 shows that the rates of substitution for (a) formylation by phosgene and V,iV-dimethylformamide, (b) acetylation by acetic anhydride and tin(IV) chloride, and (c) trifluoroacetylation with trifluoroacetic anhydride (71AHC(13)235) are all in the sequence furan > tellurophene > selenophene > thiophene. Pyrrole is still more reactive as shown by the rate for trifluoroacetylation, by the relative rates of bromination of the 2-methoxycarbonyl derivatives (pyrrole > furan > selenophene > thiophene), and by the rate data on the reaction of the iron tricarbonyl-complexed carbocation [C6H7Fe(CO)3]+ (Scheme 5) (2-methylindole ss V-methylindole > indole > pyrrole > furan > thiophene (73CC540)). 

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