3-Alkoxycarbonyl-4-carboxy

Elektronenreiche Carboxy-N-heteroarene erleichtern ebenfalls die Hydrogenolyse (anwesende Alkoxycarbonyl- bzw. Formyl- oder Acyl-Gruppen werden mitreduziert). Pyrrol-carbonsauren werden z. B. durch Lithiumalanat in Diathylather oder THF zu den entsprechenden Methyl-pyrrolen reduziert4 s z, B.4 ... 

Natriumboranat/Aluminiumchlorid wird hauptsachlich zur selektiven Reduktion von Carbonsaureestern gebraucht, die neben der Alkoxycarbonyl-Gruppe noch eine Carboxy-Gruppe (in Form des Natrium-Salzes), eine unsubstituierte Amino-carbonyl-Gruppe, eine Nitro- oder Halogcn-Gruppe enthalten. 

Stehen die Carboxy- und Alkoxycarbonyl-Gruppe giinstig zu einander, so werden Lactone erhalten z.B.4 ... 

The hydrolysis of diethyl N-(3-alkoxycarbonyl-2-thienyl)aminomethy-lenemalonates (1439, R = Me, Et) by potassium hydroxide in ethanol yielded diethyl Af-(3-carboxy-2-thienyl)aminomethylenemalonates (1439, R = H) [75GEP2435025, 75JAP(K)77393]. The treatment of the /erf-butyl esters 1439, R = rBu, R1 = R2 = H, Me, (CH2)4] with formic acid or trifluoroacetic acid at room temperature also afforded the carboxylic acid derivatives [1439, R = H, R = R2 = H, Me, (CH2)4] [75JAP(K)77394]. 

Bei 4(5)-Alkoxycarbonyl-5(4)-carboxy-imidazolen ist die thermische Abspaltung der Carboxy-Gruppe unter Erhalt der Alkoxycarbonyl-Gruppe z. B. durch Kochen in Dimethylformamid moglich523. 

Bei der Verseifung der 2-Alkoxycarbonyl- bzw. 2-Aminocarbonyl-Funktion decarboxyliert das zunachst entstehende 2-Carboxy-l,3-dimethyl-benzimidazolium-iodidzu 1,3-Dimethyl-benziinid-azoUum-iodid (81% Schmp. 196 -198°). Das Cyan-Derivat solvolysiert allerdings in hoi Bern Methanol zu l,3-Dimethyl-2-oxo-2,3-dihydro-benzimidazol (67%)499 ... 

Durch Cyclokondensation von Thiomalonsaure-0,0-dimethylester mit Carbonsaure-hydrazi-den konnen in mafligen Ausbeuten 2-(Alkoxycarbonyl-methyl)-l, 3,4-oxadiazole syn-thetisiert werden. Sie lassen sich in 2-(Carboxy-methyl)-l,3,4-oxadiazole iiberfiihren, wobei die Isolierung des Esters nicht unbedingt crforderlich ist319. 

Synthesis and Polymerization of Leuchs Anhydrides. The N-carboxy-a-amino acid anhydrides, referred to as Leuchs anhydrides or as NCAs, are synthesized either from N-alkoxycarbonyl derivatives of a-amino acids or from free amino acids. Cyclization of the amino acid derivative by SOCl2 or similar reagents was described first by Leuchs in 1906, but direct synthesis involves treating the a-amino acid or its hydrochloride with phosgene as shown in Figure 4. This method, commonly termed the Fuchs-Farthing method, is the one that is used most frequently since the N-carboxyanhydride may be freed easily from the carbamyl chloride, isocyanate derivative, and hydrogen chloride by crystallization. 

The radical addition of polyhaloalkyl halides to C = C bonds is compatible with the presence of functional substituents, such as hydroxy, alkoxy, epoxy, acetoxy, kctal, 0x0, cyano, carboxy, or alkoxycarbonyl groups. The experimental procedures are similar to those used for simple alkenes (see Table 2). 

Carboxy includes carboxy (carboxylic acids), alkoxycarbonyl (esters), carbamoyl (amides), thiocarbamoyl, hydrazinocarbamoyl (hydrazides), guanidinocarbonyl, azidocarbonyl (azides), chlorocarbonyl (acid chlorides), amidino, C-hydrazino-C-iminomethyl, C-alkoxy-C-iminomethyl (imino ethers), C-alkylthio-C-iminomethyl (iminothioethers), cyano (nitriles), C-formyl(aldehydes), dialkoxymethyl (acetals of aldehydes), C-acyl (ketones), isocyanato, and thiocyanato groups. 

Ylides carrying a-substituents derived from the carboxy group (alkoxycarbonyl, alkylthiocarbonyl, al-kylthiothiocarbonyl, cyano) have been synthesized by different routes. Ester-substituted ylides are... 

The Wolff rearrangement of six- and five-membered a-diazocycloalkanones has been extensively applied to the synthesis of highly strained frameworks. The rearrangement of an (x-diazo-cyclobutanone was reported from 2-diazo-3,4-bis(diphenylmethylene)cyclobutanone (1). The diazo ketone (1) was prepared by treatment of the 3,4-bis(diphenylmethyl-ene)cyclobutane-l,2-dione tosylhydrazone with alumina in 95% overall yield from the corresponding cyclobutanedione. Irradiation in the presence of water, alcohols and aniline afforded 1-carboxy-, 1-alkoxycarbonyl- and 1-phenylcarbamoyl-substituted 2,3-bis(diphenyl-methylene)cyclopropanes 2, respectively, in 13-87% yields. Thermal decomposition in aqueous dioxane afforded the cyclopropanecarboxylic acid 2 (X = OH) in 52% yield. ... 

FITS reagents reacted very easily with thiols in the presence of pyridine to give the perfluoroalkyl sulfides in good to high yields. S-perfluoroalkylation was selective in the case of polyfiinctional substrates. In the presence of groups such as hydroxy, carboxy, alkoxycarbonyl or dialkylamino, the sulfur atom was always selectively substituted.216 (Table 5.10)... 

Eine noch starker inliibierende Wirkung auf die a-Position als die Carboxy-Gruppe haben die Cyan-, Chlorcarbonyl-3 1 und Alkoxycarbonyl-Gruppe (s. dagegen andere Aussagen3, Tab. 21, S. 121). 

Unter Bedingungen, die zur Hydrierung des Furan-Ringes fiihren, bleiben Phenyl-Re-ste und lediglich hydrogenolytisch spaltbare Funktionen im allgemeinen unverandert (z.B. Amino-, Hydroxy-, Carboxy-, Alkoxycarbonyl-Gruppen). 

Alkyl —C —H-Bindungen mit a-standigen Carboxy-, Carboxylat-, Alkoxycarbonyl- oder Nitril-Gruppen sind vielfach ausreichend aktiviert um bei Einwirkung starker Basen depro-toniert zu werden. Die Carboxylierung der gebildeten resonanzstabilisierten Carbanionen (Enolat-Ionen) mit Kohlendioxid liefert Malonsaure-Derivate ... 

The rearrangement of O-aqrlated azlactones (or of oxazolyl carbonates) to a C-acyl-(or to a C-carboxy) azlactone takes place easily at room temperature in the presence of catalytic amounts of 4-(dimethylamino)pyridine (DMAP) or of 4-(l-pyrrolidinyl) pyridine (PPY), as first disclosed by Stegtich and Hofle in 1969 (Scheme 40.1) [9]. Although the product is usually a 4-acyl- (or a 4-alkoxycarbonyl)azlactone, if the R2 substituent is electron-donating the rearrangement at C2 can take place. 

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