S-alkoxycarbonyl

S-alkoxycarbonyl-4-oxoalkanoic acid 1,4-alkanedioic acid anhydride 1401... 

In the case of hindered enolates, the equillibrium favors reactants. Mg2+ and Zn2+ counterions will stabilize the intermediate p-alkoxycarbonyl and push the equillibrium towards products. (jAC.S 1973, 9.5,3310)... 

Olah s original preparative nitrations were carried out with mixtures of the aromatic compound and nitronium salt alone or in ether, and later with sulpholan as the solvent. High yields of nitro-compounds were obtained from a wide range of aromatic compounds, and the anhydrous conditions have obvious advantages when functional groups such as cyano, alkoxycarbonyl, or halogenocarbonyl are present. The presence of basic fimctions raises difficulties with pyridine no C-nitration occurs, i-nitropyridinium being formed. ... 

In the 1980s cost and availabiUty of acetylene have made it an unattractive raw material for acrylate manufacture as compared to propylene, which has been readily available at attractive cost (see Acetylene-DERIVED chemicals). As a consequence, essentially all commercial units based on acetylene, with the exception of BASF s plant at Ludwigshafen, have been shut down. AH new capacity recendy brought on stream or announced for constmction uses the propylene route. Rohm and Haas Co. has developed an alternative method based on aLkoxycarbonylation of ethylene, but has not commercialized it because of the more favorable economics of the propylene route. 

Die Verbindung reduziert in HMPT Jod-alkane, ohne Alkoxycarbonyl-, Aminocarbo-nyl- und Oxo-Gruppen anzugreifen, in saurer Losung werden Aldehyde selektiv neben Ketonen (s.S. 294) reduziert. 

Aliphatische Nitro-Verbindungen mit flankierenden elektronenanziehenden Gruppen (z. B. Oxo, Alkoxycarbonyl, Nitro, Nitroso usw.) unterliegen bei der Reduktion mit Li-thiumalanat oft einer CNt,2Cx-Spaltung (s. S. 472f.). 

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 ... 

Die selektive Reduktion der Oxo-Gruppe neben der Alkoxycarbonyl-Gruppe wird zweckmaGig mit Lithium-tri-tert.-butyloxy-hydrido-aluminat9 Oder mit Natrium- bzw. Kalium-boranat (s. S. 217, 317 ff.) durchgefiihrt. 

Die Reduktion der Alkoxycarbonyl-Gruppe zur Methyl-Gruppe verlauft auch bei der Reaktion enolisierbarer /S-Dicarbonyl-Verbindungen mit Lithiumalanat6 (s. S. 204). 

Kernstandige heteroaromatische Carbonsaure-ester mit einem elektronenliefernden Heteroring der Pyridin-3, Pyrimidin-4, Indol-5, Thiophen-6 und 1,3-Thiazol-Reihe7 werden mit Lithiumalanat zu den Methyl-Derivaten reduziert. Pyrrol-carbonsaure-estcr lassen sieh in Tetrahydrofuran oder Diathylather meist leiehter zu den Methyl-pyrrolen reduzieren als die entsprechenden Carbonsauren (s. S. 171). Die N-Alkoxycarbonyl-Gruppe wird wahrend der Reaktion abgespalten (vgl. S. 237). 

Die elektrophilen Hydride Diboran, Aluminiumhydrid und Lithiumala-nat/Aluminiumchlorid (1 1) reduzieren Lactame meist schneller und selektiver als Li-thiumalanat. Die Reduktion mit Diboran ist ahnlich wie bei den Carbonsaure-amiden3 in siedendem THF in einigen Stunden4 unter Erhalt der Alkoxycarbonyl-5 und Sulfo-Grup-pen6 beendet (s.a. S. 238f., 242). 

Verseifung der Alkoxycarbonyl-Gruppe und Reduktion der freien Oxo-carbonsaurc, wobei aber mit der Bildung von Lacton gerechnet werden muB4 (s.a.S. 31 Iff.)... 

Die Reduktion von Tosyl-hydrazonen mit Hydriden zu Kohlenwasserstoffen stellt eine praparativ vorteilhafte Variante der Wolff-Kishner-Reduktion dar. Diese Methode ermoglicht durch geeignete Wahl des Reduktionsmittels die selektive Reduktion von p-Tosyl-hydrazonen unter Erhalt von Alkoxycarbonyl-, Aminocarbonyl-, Cyan- und Ni-tro-Gruppen. Zur Reaktion ist manchmal auch ein Gemisch der Oxo-Verbindung mit To-syl-hydrazin6 anwendbar. Die Reaktion verlauft ahnlich wie bei den Diazonium-Salzen (s. S. 484) iiber das entsprechende Diazen7 8 ... 

Zur reduktiven Abspaltung der Alkoxycarbonyl-Gruppen in 1,2-Dialkoxycarbonyl-1,2-diaza-cycloalkanen zu 1,2-Diaza-cycloalkanen s. Lit.8. 

In Semmelhack s synthetic approach to plakortones, a palladium(II)-promoted intramolecular alkoxycarbonylation was used as a key step to form the tetrahydrofuran-fused y-lactone framework 101 <00TL3567>. 

V-(2-Alkoxycarbonyl-3-thienyl)aminomethylenemalonates (891) were stable even under drastic thermal conditions, but were smoothly cyclized in polyphosphate at 130°C to give thieno[3,4-/>]pyridine-3,6-dicarboxylates (892) [80JCR(S)4]. 

Kagan H, Namy JL (1999) Influence of Solvents or Additives on the Organic Chemistry Mediated by Diiodosamarium. 2 155-198 Kakiuchi F, Murai S (1999) Activation of C-H Bonds Catalytic Reactions. 3 47-79 Kakiuchi F, Chatani N (2004) Activation of C-H Inert Bonds. 11 45-79 Kalck P, Urrutigoi ty M, Dechy-Cabaret O (2006) Hydroxy- and Alkoxycarbonylations of Alkenes and Alkynes. 18 97-123 Kanno K, see Takahashi T (2005) 8 217-236 Keen SP, see Gibson SE (n6e Thomas) (1998) 1 155-181 Kendall C, see Wipf P (2005) 8 1-25... 

Interest in the uses of HMPT has also been maintained, but a warning has been issued (by the E. I. du Pont de Nemours Company and the U.S. National Institute for Occupational Safety and Health) about its potential acute toxicity. HMPT has been used in the synthesis of 2,4-bis(dimethylamino)qui nolines,9 8 as a solvent for reactions between carbonyl compounds and sulphur," for the conversion of iV-benzylcarbox-amides into 3-phenylpropionitriles,100 in reactions between metals or organometallic compounds with a variety of organic substrates,101 and as a solvent for alkylation reactions of /J-keto-esters and related compounds in which the alkylation reaction is accompanied by de(alkoxycarbonylation) (Scheme 7).102... 

Considering the monoaminomercuration-demercuration of 1,4-hexadiene with /V-me-thylaniline leads to V-methyl-lV-(l-methylpent-3-enyl)aniline, the stereoselective synthesis of /V-alkoxycarbonyl or /V-tosyl s-2,5-dimethylpyrrolidine from the same diene has been explained172 on the basis of an initial amidomercuration reaction on the terminal bond followed by the second addition of mercury(II) salt to the internal double bond, on the less sterically hindered site (equation 171). 

L. S. Nielsen, F. Slpk, H. Bundgaard, W-Alkoxycarbonyl Prodrugs of Mebendazole with Increased Water Solubility , Int. J. Pharm. 1994, 102, 231 -239. 

Ferrero, M., Fernandez, S. and Gotor, V., Selective alkoxycarbonylation of A-ring precursors of vitamin D using enzymes in organic solvents. Chemoenzymatic synthesis of lo ,25-dihydroxyvi-tamin D3 C-5 A-ring carbamate derivatives. J. Org. Chem., 1997, 62, 4358. 

Chirality derived from the readily accessible a-amino acids has been incorporated into the side chains of aza and diaza macrocyclic polyethers. A number of procedures suitable for peptide synthesis have proved (178) to be unsuitable for acylating the relatively unreactive secondary amine groups of aza crown ethers. Eventually, it was discovered that mixed anhydrides of diphenylphos-phinic acid and alkoxycarbonyl-L-alanine derivatives do yield amides, which can be reduced to the corresponding amines, e.g., l-172. By contrast, the corresponding bisamides of diaza-15-crown-S derivatives could not be reduced and so an alternative approach, involving the use of chiral A-chloroacetamido alcohols derived from a-amino acids, has been employed (178) in the synthesis of chiral receptors, such as ll-173 to ll-175, based on this constitution. 

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