Pyrrole 2-methyl-, 3-ethyl ester

Pyrrole-3-carboxylic acid, 2,5-dimethyl-ethyl ester formylation, 4, 217 Pyrrole-3-carboxylic acid, 2-methyl-ethyl ester... 

H-Pyrrole-2-carboxylic acid, 4-acetyl-3-ethyl-5-methyl-, ethyl ester X-ray, 4, 6, 160 <72JCS(P2)902>... 

The most successful modifier is cinchonidine and its enantiomer cinchonine, but some work in expanding the repertoire of substrate/modifier/catalyst combinations has been reported (S)-(-)-l-(l-naphthyl)ethylamine or (//)-1 -(I -naphth T)eth Tamine for Pt/alumina [108,231], derivatives of cinchona alkaloid such as 10,11-dihydrocinchonidine [36,71], 2-phenyl-9-deoxy-10, 11-dihydrocinchonidine [55], and O-methyl-cinchonidine for Pt/alumina [133], ephedrine for Pd/alumina [107], (-)-dihydroapovincaminic acid ethyl ester (-)-DHVIN for Pd/TiOz [122], (-)-dihydrovinpocetine for Pt/alumina [42], chiral amines such as 1 -(1 -naphtln I)-2-(I -pyrro 1 idiny 1) ethanol, l-(9-anthracenyl)-2-(l-pyrrolidinyl)ethanol, l-(9-triptycenyl)-2-(l-pyrrol idi nyl)cthanol, (Z )-2-(l-pyrrolidinyl)-l-(l-naphthyl)ethanol for Pt/alumina [37,116], D- and L-histidine and methyl esters of d- and L-tryptophan for Pt/alumina [35], morphine alkaloids [113],... 

The synthesis of pyrrolo[2,3- 7 pyridazines can be achieved by starting either with pyridazine, a tetrazine, or a pyrrole. Pyridazinone 80 reacts with bromomethyl derivatives to give poor yields of 81 <1996H(43)1863> (Equation 34), while 5-acetyl-2-methyl-4-nitro-6-phenyl-3(2//)-pyridazinone, after treatment with sarcosine ethyl ester for a brief time at room temperature, followed by acid hydrolysis afforded a good yield of 82 (70%) <1994S669>. 

Michael adducts are also formed from the reactions of pyrroles with ethyl propiolate and with but-l-yn-3-one. In addition to the expected acrylic ester, 1-methylpyrrole also yields ethyl 3,3-bis(l-methyl-2-pyrrolyl)propanoate in its reaction with ethyl propiolate (67MI30500, 67MI30501), whilst if both a -positions of the pyrrole ring are unsubstituted, a twofold Michael addition with but-l-yn-3-one occurs to give the 2,5-disubstituted pyrrole (76JHC1145). 

A comparison of the absorption and fluorescence properties of 3,5-diaryl-l//-pyrrole-2-carboxylic acid ethyl esters reveals marked effects of/i-dimethylamino and o-methyl substituents on the phenyl group at C-3 and suggests that in the presence of these substituents emission occurs either from a charge transfer state or from a combination of charge transfer and locally excited states <2005NJC1258>. 

Synthesis of pyrrales. A key step in a new synthesis of pyrroles is the base-catalyzed condensation of methyl vinyl ketone with an N4osyl amino acid ester, for example N-tosylglycine ethyl ester (1). Dehydration of the pyrrolidine (2)... 

Ludwig. This compound has an empirical formula corresponding to structure (1) and shows the ultraviolet and infrared" absorptions of a pyrrole-3-carboxylic ester. Its acetylation gives a tetra-O-acetyl derivative." Oxidation with lead tetraacetate yields ethyl 5-formyl-2-methyl-pyrrole-3-carboxylate (4), identical with the compound prepared in a different way. Oxidation with potassium permanganate in alkaline solution at low temperature yields 3-(ethoxycarbonyl)-2-methylpyrrole-5-carboxylic acid (7) which can be transformed " into the diethyl ester (8), identical... 

Pyrrole-2-carboxylic acid esters. 2-Methyl-3-ethoxyacrolein added dropwise with stirring to N-benzylglycine ethyl ester under N2, heated at 100° for 2 h, treated with NaOEt in ethanol, and refluxed for 2 h product. Y 48%. F.e.s. G.H. Walizei, E. Breitmaier, Synthesis 1989, 337-40. 

The use of carbonyl function is classic approach in heterocyclic synthesis. In case of fluorinated pyrroles this approach was frequently used. Convenient method for synthesis of pyrroles 221 is based on the reaction of fluorinated 5-keto acid esters or amides 220 with ammonia. In case of methyl and ethyl esters amidolysis was... 

The syntiiesis of DPP-4 inhibitor, Saxagliptin 1 (Figure 4.21) required key intermediate (5S)-5-aminocarbonyl-4,5-dihydro-lH-pyrrole-l-carboxylic acid,l-(l,l-dimethyl ethyl)-ester 76 [22-24]. Direct chemical ammonolysis resulted in unacceptable levels of amide racemization and side-product formation. Milder, two-step hydrolysis-condensation protocols using coupling agents such as 4-(4,6-dimetiioxy-l,3,5-triazin-2-yl)-4-methyl-morpholinium chloride (DMT-MM) were compromised by reduced overall yields [103]. 

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