Oxycarbonylation

H a NH arginine guanidinium cation N,Nbis (adamantyl-oxycarbonyl) = Adoc pH< 10 iQA. H+... 

The intramolecular oxidative earbonylation has wide synthetie applieation. The 7-lactone 247 is prepared by intramolecular oxycarbonylation of the alke-nediol 244 with a stoichiometric amount of Pd(OAc)2 under atmospheric pres-sure[223]. The intermediate 245 is formed by oxypalladation, and subsequent CO insertion gives the acylpalladium 246. The oxycarbonylation of alkenols and alkanediols can be carried out with a catalytic amount of PdCl2 and a stoichiometric amount of CuCb, and has been applied to the synthesis of frenolicin(224] and frendicin B (249) from 248[225]. The carbonylation of the 4-penten-l,3-diol 250, catalyzed by PdCl2 and CuCl2, afforded in the c -3-hydroxytetrahydrofuran-2-aeetie acid lactone 251[226J. The cyclic acetal 253 is prepared from the dienone 252 in the presence of trimethyl orthoformate as an accepter of water formed by the oxidative reaction[227]. 

CO, and methanol react in the first step in the presence of cobalt carbonyl catalyst and pyridine [110-86-1] to produce methyl pentenoates. A similar second step, but at lower pressure and higher temperature with rhodium catalyst, produces dimethyl adipate [627-93-0]. This is then hydrolyzed to give adipic acid and methanol (135), which is recovered for recycle. Many variations to this basic process exist. Examples are ARCO s palladium/copper-catalyzed oxycarbonylation process (136—138), and Monsanto s palladium and quinone [106-51-4] process, which uses oxygen to reoxidize the by-product... 

The other CO route for adipic acid manufacture involves 1,4-addition of CO and O2 to butadiene to produce an intermediate, which is subsequently hydrogenated and hydroly2ed to adipic acid (50). This is called the oxycarbonylation process. Both the BASF and the oxycarbonylation processes have been intensively investigated. 

Another alternative method to produce sebacic acid iavolves a four-step process. First, butadiene [106-99-0] is oxycarbonylated to methyl pentadienoate which is then dimerized, usiag a palladium catalyst, to give a triply unsaturated dimethyl sebacate iatermediate. This unsaturated iatermediate is hydrogenated to dimethyl sebacate which can be hydrolyzed to sebacic acid. Small amounts of branched chain isomers are removed through solvent crystallizations giving sebacic acid purities of greater than 98% (66). 

The relative stereostructure of 9-acetyl-7-hydroxy-l,2-dimethyl-7-meth-oxycarbonyl-4-phenyl-6-oxo-l, 4,7,8-tetrahydro-6/7-pyrido[l, 2-u]pyri-midine-3-carboxylate 122 was justified by an X-ray diffraction analysis (97JOC3109). The stereochemistry and solid state structure of racemic trans-6,9-//-l, 6-dimethyl-9 z-ethoxy-9-hydroxy-4-oxo-l,6,7,8,9,9 z-hexahydro-4//-pyrido[l,2- z]pyrimidine-3-carboxylate (123), adopting a cw-fused conformation, were determined by X-ray investigations (97H(45)2175). 

Reaction of 9,10-difluoro-7-oxo-2,3-dihydro-7//-pyrido[l, 2,3- e]-1,4-ben-zothiazine-6-carboxylic acid and its ethyl ester with B(OH)3 in AC2O in the presence of ZnCl2 afforded 6-[(diacetoxyboryl)oxycarbonyl] derivative 323 (R = OAc)], which was reacted with primary and cyclic amines to give 10-amino-9-fluoro-7-carboxylic acid derivatives 324 (97MI41, 98MI30). 6-[(Difluoroboryl)oxycarbonyl derivative 323 (R = F) was obtained from ethyl 9,10-difluoro-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylate with BF3-THF complex. Reaction of 323 (R = F) and 1-methylpiperazine in DMF at 50-60 °C and subsequent acidic hydrolysis afforded 7 (97MI1). 

To a 1 liter flask containingdimethylformamideatO°C, was added 24.8 g sodium N-(2-meth-oxycarbonyl-1-methylvinyD-D-Ct-phenylglycine (prepared from sodium D-Ct-phenylgiycine and methyl acetoacetate). The mixture was cooled to -40°C and methyl chloroformate (7.5... 

Amino-5-phenylthiomethoxyacetanilide in methanol solution is heated with N,N -bis-meth-oxycarbonyl-isothiourea-S-methyl ether with the addition of a catalytic amount of p-toluene-sulfonic acid for three hours with stirring under reflux. The mixture is then filtered hot and after cooling the febantel product crystallizes out. It is filtered off, rinsed with ether and dried under high vacuum to give the final product, melting at 129°C to 130°C. 

The optically active 1,3-/ram-substitutcd tetrahydro-/f-carboline 3 is obtained predominantly on treatment of the imine 2, derived from L-tryptophan and isovaleraldehyde, with A-benzyl -oxycarbonyl-L-prolyl chloride145. 

NMe W-methyl, /-Leu te(f-leucine, L-neo-Trp (2S)-2-amino-3-(fW-4-indolyl)propanoicacid, Boc /-butyl-oxycarbonyl, f pseudopeplidebond. 

Diboran kann zur selektiven Reduktion der Halogencarbonyl-Gruppe neben einer Alk-oxycarbonyl-Gruppe herangezogen werden z.B.18 ... 

Poly(2,4-hexadiyne-l,6-ylene carbonate) (Poly(oxycarbonyl-2,4-hexadiyne-1,6-diyl))... 

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