Esters acetamidation

A highly selective ring opening of 6-azabicyclo[3.2.0]hept-3-en-7-one (45) was achieved by using a whole cell preparation of ENZA-1 (Rhodococcus equi) [20, 86, 87]. The hydrolysis selectively gave the amino acid 46, which was converted directly to the ester acetamide 47. The recovered lactam 48 was reduced to 49. This was hydrolysed to 5, which displayed a similar optical rotation to that of natural cispentacin (Scheme 7). It is worthy of mention that ENZA-1 exhibited only poor hydrolytic activity towards ( )-49. 

A series of 3-deoxy compounds derived from methyl a-o-glucopyranoside were obtained via iV,iV-dimethylsulphamoyl esters which underwent efficient reductive cleavage on treatment with sodium in liquid ammonia under conditions in which acetal, ester, acetamide, and azido groups were stable. The required esters were prepared by use of V,A-dimethylsulphamoyl chloride, or with sulphuryl chloride in pyridine, followed by dimethylamine. Other... 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

Chapter III. 1 Heptene (111,10) alkyl iodides (KI H3PO4 method) (111,38) alkyl fluorides (KF-ethylene glycol method) (111,41) keten (nichrome wire method) (111,90) ion exchange resin catalyst method for esters (111,102) acetamide (urea method) (111,107) ethyl a bromopropionate (111,126) acetoacetatic ester condensation using sodium triphenylmethide (111,151). 

One of the virtues of the Fischer indole synthesis is that it can frequently be used to prepare indoles having functionalized substituents. This versatility extends beyond the range of very stable substituents such as alkoxy and halogens and includes esters, amides and hydroxy substituents. Table 7.3 gives some examples. These include cases of introduction of 3-acetic acid, 3-acetamide, 3-(2-aminoethyl)- and 3-(2-hydroxyethyl)- side-chains, all of which are of special importance in the preparation of biologically active indole derivatives. Entry 11 is an efficient synthesis of the non-steroidal anti-inflammatory drug indomethacin. A noteworthy feature of the reaction is the... 

Esters are named by replacing the ending -ic acid with the suffix -ate. The alcohol portion of the ester is named by replacing the -ane ending of the parent hydrocarbon name with the suffix -yl. The alkyl radical name of an ester is separated from the carboxylate name, eg, methyl formate for HCOOCH. Amides are named by changing the ending -oic acid to -amide for either systematic or common names, eg, hexanamide and acetamide. 

The most convenient synthesis of 6-hydroxy-2-pyridones is by the condensation of a P-ketoester, eg, ethyl acetoacetate, with an active methylene compound, eg, malonic ester, cyanoacetic ester, and an amine. The amine can be omitted if an acetamide is used and in some cases this modification results in a higher yield. 

A newer method for the preparation of nitronic esters, namely utilizing the (9-trimethyl-silyl ester, has been reported and these are prepared by the reaction of alkylnitro compounds and (V,(V-bis(trimethylsilyl)acetamide. These nitronic esters also undergo cycloaddition with alkenes to produce isoxazolidines (equation 54) (74MIP41601, 74DOK109, 78ACS(B)ll8). 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

If ki = ki, p7/min = U2 pA" . This is an unusual condition it has been observed in the hydrolysis of acetamide at 100°C. Since pA" = 12.32 at 100°C, the minimum rate in this reaction occurs at pH 6.16. For ester hydrolyses, ki is usually greater than ki, and the minimum is observed near pH 5-6 (at room temperature). Equation (6-57) is used in the construction of a calculated pH-rate profile, when it allows... 

The A-substituted derivatives of 4-oxo-4//-pyrido[l,2-n]pyrimidine-3-carboxamides and -3-acetamides and l,6-dimethyl-4-oxo-1,6,7,8-tetrahy-dro-4//-pyrido[l,2-n]pyrimidine-3-carboxamide were prepared by treatment of the appropriate 3-carboxylic acids and acetic acid, first with an alkyl chloroformate in the presence ofNEt3 in CHCI3 below — 10°C, then with an amine (98ACH515). A-Phenethyl and A-[2-(3,4-dimethoxyphenyl)ethyl] derivatives of 6-methyl-6,7,8,9-tetrahydro-4//-pyrido[l, 2-n]pyrimidine-3-acetamide were obtained in the reaction of 6-methyl-6,7,8,9-tetrahydro-4//-pyrido[l,2-n]pyrimidine-3-acetic acid and phenethylamines in boiling xylene under a H2O separator. Hydrazides of 4-oxo-4//- and 4-oxo-6,7,8,9-tetrahydro-4//-pyrido[l, 2-n]pyrimidine-3-acetic acid were prepared from the appropriate ester with H2NNH2 H2O in EtOH. Heating 4-oxo-4//- and 6-methyl-4-oxo-6,7,8,9-tetrahydro-4//-pyrido[l, 2-n]pyrimidine-3-acetic hydrazides in EtOH in the presence of excess Raney Ni afforded fhe appropriafe 4-oxo-6,7,8,9-fefrahydro-4//-pyrido[l,2-n]pyrimidine-3-acefa-mide. In the case of the 4-oxo-4// derivative, in addition to N-N bond... 

How much acetamide can be made from 3.1 grams of methyl acetate See equation (27), p. 338. Assume the ester is completely converted. 

Hematoporphyrin dimethyl ester (15, 1.52 g, 2.43 mmol) (diastereomeric mixture) and Af.At-dimethyl-acetamide dimethyl acetal (8 mL) were suspended in o-xylcnc (100 mL), degassed and then heated with exclusion of light in a flask equipped with a reflux condenser and a Soxhlet apparatus containing 3 A molecular sieves. The temperature was raised during 15 min from rt to 115 C and kept at this temperature for 30 min. Then the temperature was raised to 155 C and the mixture kept at this temperature for 3 h. The mixture was evaporated in a bulb tube and the residue subjected to column chromatography [silica gel (ICN), CH2Cl2/MeOAc/MeOH 10 5 0.5] with exclusion of light yield of pure 16A 305 mg (17 %) yield of pure 16B, 375 mg (20%) and 187 mg (10%) of a mixture of 16 A and B. 

This is by far the most versatile route to the synthesis of ester-substituted aziridines, especially as the benzhydryl group can easily be cleaved by hydrogenolysis. Wulff has applied this methodology to a short asymmetric synthesis of the antibiotic (-)-chloramphenicol in four steps from p-nitrobenzaldehyde (Scheme 1.34) [61]. In this case it was found that treatment of the aziridine 111 with excess dichloroacetic acid gave the hydroxy acetamide directly, so no separate deprotection step was required. 

Abietylamine, dehydro-, A tnfluoro- [Acetamide, 2,2,2-trifluoro-/V-[ [1,2,3,4,4a, 9,10,1 Oa-octahydro-l, 4a-dtmethyl-7-(l-methylethyl)-l -phenanthrenyl ] -methyl]-, [17 (la,4ad,10aa))-, 125 Acetamides, A-arylalkyl-, 7 Acetanilide, 2,2,2-tnfluoro- [Acetamide, 2,2,2-tnfluoroTV-phenyl-], 122 Acetic acid, cyano-, methyl ester, 63 Acetic acid, methoxy-, 70 Acetic acid, phenoxy-, 68 Acetic acid, phenyl- [Benzeneacetic acid],... 

Acid (0.78 M), neutralized to 25% Pt-anode, 0.25 A/cm Alcohol, ester, ether and acetamide according to solvent Sodium salt Tetrabutylammonium-salt... 

C23H34O, 1054-83-7) see Metenolone acetate lV-[(3p,17P)-3-(acetyloxy)androst-5-en-17-yl]acetamide (C23H35NO3 4350-67-8) see Prasterone [R-(/, R )]-a-(acetyloxy)benzeneacetic acid l-(2-prope-nyl)dodecyl ester... 

C 2HijF,N202 90357-51-0) see Bicalutamide 4 -cyano-3 -trifIuoromethylmethacrylanilide (CijHijFjNjO 90357-53-2) see Bicalutamide Af-[4-cyano-2-(trifluoromethyl)phenyl]acetamide (C (,H7F,N20 175277-96-0) see Mabuterol /V-(4-cyano-3-trifluoromethylphenyl)-3-(fluorophenyl-sulfanyl)-2-hydroxy-2-methylpropionamide (C,hH,4F4N202S 90356-78-8) see Bicalutamide 2-cyano-3-(3,4,5-trimethoxyphenyl)-2-propenoic acid ethyl ester... 

The carboxyl group of 2-[4-(4-carboxybenzoyl)benzyloxy]-3-methyM77-pyrido[l,2- ]pyrimidin-4-one, prepared by hydrolysis of the methyl ester, was reacted first with (Et02C)20 in DMF at room temperature and then with 4-phenylpiperazine and 4-piperidinopiperidine to give the appropriate amide derivatives <1996EPP733633>. The N-substituted derivatives of 4-oxo-477-pyrido[l,2-tf]pyrimidine-3-carboxamides and -3-acetamides and 1,6-dimethyl-4-oxo-l,6,7,8-tetrahydro-477-pyrido[l,2-tf]pyrimidine-3-carboxamide were prepared by treatment of the appropriate... 

Acyl hydrazides are useful precursors for the synthesis of 1,2,4-triazoles. Reaction of acyl hydrazides 149 with imidoylbenzotriazoles 148 in the presence of catalytic amounts of acetic acid under microwave irradiation afforded 3,4,5-trisubstituted triazoles 150 <06JOC9051>. Treatment of A-substituted acetamides with oxalyl chloride generated imidoyl chlorides, which reacted readily with aryl hydrazides to give 3-aryl-5-methyl-4-substituted[ 1,2,4]triazoles <06SC2217>. 5-Methyl triazoles could be further functionalized through a-lithiation and subsequent reaction with electrophiles. ( )-A -(Ethoxymethylene)hydrazinecarboxylic acid methyl ester 152 was applied to the one-pot synthesis of 4-substituted-2,4-dihydro-3//-1,2,4-triazolin-3-ones 153 from readily available primary alkyl and aryl amines 151 <06TL6743>. An efficient synthesis of substituted 1,2,4-triazoles involved condensation of benzoylhydrazides with thioamides under microwave irradiation <06JCR293>. 

Sulfosuccinimidyl-2-(7-azido-4-methylcoumarin-3-acetamide)ethyl-l,3 -dithiopropionate (SAED) is a photoreactive heterobifunctional crosslinking agent that also contains a fluorescent group (Thermo Fisher). The sulfo-NHS ester end of the reagent reacts with primary amines in proteins and other molecules to form stable amide linkages. The photoreactive end is an AMCA... 

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