Dicarboxylic derivs

The cyclocondensation of an aldehyde, CH-acidic ketone and ammonia provides symmetrical l,4-dihydropyridine-3,5-dicarboxylate derivatives of pharmacological importance, often called Hantzsch 1,4-dihydropyridines (1,4-DHPs) following its original invention over a century ago (Scheme 4) [44,45]. The 1,4-DHP motif is found in a number of chemotherapeutic agents for... 

The catalyst was prepared from the corresponding chiral diol and TiCl2(OPr-/)2 at room temperature in the presence of 4 A molecular sieves. Without molecular sieves, stoichiometric amounts of the titanium complex were required to obtain an equally high enantioselectivity. A remarkable solvent effect was observed. Various cycloadducts were only obtained with high optical yields when non-polar solvents were employed252,253. For example, 4-substituted 4-cyclohexene-1,2-dicarboxylate derivatives 408 were obtained with ee values ranging from 91 to 94% in the reactions of 91a, 399 and 407 with 17b in toluene/... 

Copolymers - [COPOLYMERS] (Vol 7) - [DEFOAMERS] (Vol 7) -dicarboxylic derivatives in [DICARBOXYLIC ACIDS] (Vol 8) YractLonationusing SCFs [SUPERCRITICALFLUIDS] (Vol 23) -ofLDPE [OLEFIN POLYMERS-POLYETHYLENE - LOW DENSITY POLYETHYLENE] (Vol 17) -of poly(vmyl acetals) [VINYL POLYMERS - VINYL ACETAL POLYMERS] (Vol 24)... 

Heat-transfer fluids -antifreeze as [ANTIFREEZES AND DEICING FLUIDES] (Vol 3) -dicarboxylic derivatives m [DICARBOXYLIC ACIDS] (Vol 8) -organotm catalysts for [TIN COMPOUNDS] (Vol 24) -propylene oxide m mfg of [PROPYLENE OXIDE] (Vol 20) -terphenyl mixtures [BIPHENYL AND TERPHENYLS] (Vol 4)... 

Hot-melt coatings -dicarboxylic derivatives m [DICARBOXYLIC ACIDS] (Vol 8)... 

The first report of cycloaddition reactions of 3-dimethylamino-1 -methyl-1,2,4-triazinium-5-olates (71) with DMAD shows that 4-dimethylamino-l-methyl -6-oxo-l,3a,6,6a-tetrahydro-pyrrolo[3,4-c]pyrazole-3,3a-dicarboxylate derivatives (72) are obtained in each case [95AJC1175]. 

The aldehyde (0.38 mmol, 1.5 equiv), the catalyst (10 mol%), and benzoic acid (10 mol%) were stirred in toluene and cooled to —15 °C. The thiol (1 equiv) was added and the reaction mixture stirred for 30 min. Diazo dicarboxylate derivative (1.3 equiv) was added and the reaction progress monitored by TLC (3-24 h). The crude reaction mixture was diluted with MeOH (2 mL) and cooled to 0 °C, followed by the addition of NaBH4 (2 equiv). After 10 min, 2 M NaOH (2 mL) and THF (2 mL) were added and the crude reaction mixture was stirred for 2 h. After standard aqueous work-up, the product was purified by FC on silica gel. 

The l,4-dihydro-2,6-dimethyl-4-(2- or 3-nitrophenyl)-3,5-pyridine-dicarboxylate derivatives nifedipine (NF), nitrendipine (NT), and nimodipine (NM) were supplied by Bayer AG (Wuppertal, Germany). Analytical grade reagents were used at all times, toluene AR (Riedel-de-Haen AG, Seelze, Germany) was distilled over a 50 cm Vigreux column before use. Sodium hydroxide, 0.5 mol/L, was purchased from J.T. Baker Chemical Corp. (USA) and the amber screw-cap autosampler bottles (2 mL) were obtained from Pierce Biotechnology Inc. (Rockford IL USA) and rinsed with acetone before use. 

HOMOCONJUGATE ADDITION OF NUCLEOPHILES TO CYCLOPROPANE-1,1-DICARBOXYLATE DERIVATIVES PREPARATION OF 2-OXO-1-PHENYL-3-PYRROLIDINECARBOXYLIC ACID... 

Oxidation of secondary hydroxyl groups at C-2 and C-3 leads to acyclic dialde-hydes and dicarboxylic derivatives. Selective oxidation of primary hydroxyl groups is more difficult, but can be achieved by stoichiometric as well as catalytic methods. Nitric acid oxidizes monosaccharides into aldaric acids. Oxidation of cellulose or starch by nitrogen dioxide (N2O4) yields 6-carboxy starch and 6-carboxycellulose respectively. Subsequent hydrolysis under well-controlled conditions (0.5-2 M HCl at 150 °C) of these materials yields o-glucuronic acid (o-GlcAp) [12]. 

The presence of a double bond in the unsaturated acids leads to an opprountiy for isomerism like that shown by crotonic and isocrotonic acids (127). The two forms in the case of the dicarboxyl derivatives of ethylene are represented by the formulas —... 

Both maleic and fumaric acid are reduced by sodium amalgam to succinic acid—a reaction which is evidence of the correctness of the view that they are dicarboxyl derivatives of ethylene —... 

Benzo[Z ]thieno[3,2- ]benzo[fe]thiophene-2,7-dicarboxylate derivatives exhibit... 

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