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Mannich reaction products

Thus, reduction of the Mannich reaction product (65) from acetophenone leads to alcohol 66. Replacement of the hydroxyl group by chlorine (67) followed by displacement of halogen with the anion from o-cresol affords the ether 68. Removal of one of the methyl groups on nitrogen by means of the von Braun reaction or its modem equivalent (reaction with alkyl chloroformate followed by saponification) leads to racemic 69 which is then resolved with L-(+)-mandelic acid to give the levorotary antidepressant tomoxetine (69) [16]. [Pg.30]

Enantioselective Direct Mannich Reaction Products with One Stereogenic Center... [Pg.97]

Masui,, M., Suda, K.,Yamauchi, M., and Yoshida, N Novel Mannich reaction product from 2.4 5)-diisopropylimidazolc, Chem. Pluimi. Bull. Tokyo, 21, I.S87, 197.3. [Pg.75]

Kunz and coworkers [248, 365] have proposed imines derived from carbohydrates 1.101 as heterodienophiles. The ZnCh-mediated cycloadditions of these imines to denes are not very selective, except with Danishefsky s diene 3.26 (R = R = Me, R" = RM = H). According to the inline R substituent, the reaction product is either cycloadduct 9.79 or the Mannich reaction product 9.80. The lal-... [Pg.580]

Even though any modification of C-2 leads to inferior activity, or none at all, the pyrro-lidinomethyl derivative of the 2-carboxamide (rolitetracycline) appears to be an exception. However, on closer scrutiny this Mannich reaction product (Eq. 6.12) will be seen as a prodrug of TC. The compound is 2,500 times more water soluble than the parent TC compound (comparing free bases), to which it hydrolyzes in vivo. Thus its activity is essentially that of the parent compound. [Pg.245]

Other complex mixtures involving Mannich reaction products of use as anti-rust additives in lubricating oils have included the reaction of fatty acids (RCO2H), nonylphenol, with diethylenetriamine or triethylenetriamine and aqueous formaldehyde. It would appear that the primary amine groups result in amide formation at 160-180°C and the residual secondary amine group then undergoes a Mannich reaction in the usual way with t-octyllphenol and... [Pg.375]

As stated earlier, resolution processes give a maximum yield of 50% of the desired enantiomer, but in practice it is usually less than 40%. The yield can be raised beyond 50% if the diastereomer that remains in solution can be made to undergo spontaneous epimerization. An example is the synthesis of dextropropoxyphene by asymmetric transformation of the diastereomeric salt formed from the Mannich reaction product using dibenzoyl-L-tartaric acid (reaction 9.3). [Pg.252]

A Mannich reaction product has been S5mthesized that shows a good detergency performance in hydrocarbon fuels. The Mannich reaction product is prepared from a PlB-substituted phenol, an aldehyde and ethylenediamine, where the PIB has at least 70% vinylidene double bond isomer (28). [Pg.182]

For the Mannich reaction, the PIB alkylated phenol in an aromatic solvent is charged into the reactor. Formalin was charged to the reactor at 48°C and dimethylamine in water solution was charged to the reactor over 2 /i at 48°C. Then, the mixture was heated to 99°C to attain full reflux. Afterwards, the mixture was gradually heated to 130°C and held at 130°C for 2 h. Finally, the mixture was vacuum distilled at 130°C to remove the remaining water. The resultant mixture was filtered through diatomaceous earth to give the Mannich reaction product. [Pg.182]

Indole (I) condenses with formaldehyde and dimethylamine in the presence of acetie acid (Mannich reaction see Section VI,20) largely in the 3-position to give 3 dimethylaminomethylindole or gramine (II). The latter reaets in hot aqueous ethanol with sodium cyanide to give the nitrile (III) upon boiling the reaction mixture, the nitrile undergoes hydrolysis to yield 3-indoleaeet-amide (IV), part of which is further hydrolysed to 3-indoleacetic acid (V, as sodium salt). The product is a readily separable mixture of 20 per cent, of (IV) and 80 per cent, of (V). [Pg.1012]

There also exists an acidregioselective condensation of the aldol type, namely the Mannich reaction (B. Reichert, 1959 H. Hellmann, 1960 see also p. 291f.). The condensation of secondary amines with aldehydes yields Immonium salts, which react with ketones to give 3-amino ketones (=Mannich bases). Ketones with two enolizable CHj-groupings may form 1,5-diamino-3-pentanones, but monosubstitution products can always be obtained in high yield. Unsymmetrical ketones react preferentially at the most highly substituted carbon atom. Sterical hindrance can reverse this regioselectivity. Thermal elimination of amines leads to the a,)3-unsaturated ketone. Another efficient pathway to vinyl ketones starts with the addition of terminal alkynes to immonium salts. On mercury(ll) catalyzed hydration the product is converted to the Mannich base (H. Smith, 1964). [Pg.57]

The yields of this reaction are typically 40—80%. C-nmr studies (41) indicate that the reaction is a second-order process between polyacrylamide and dim ethyl am in om eth an ol, which is one of the equiUbrium products formed in the reaction between formaldehyde and dimethylamine [124-40-3] C2H2N. The Mannich reaction is reversible. Extensive dialysis of Mannich polyacrylamides removes all of the dimethyl aminomethyl substituents (42). [Pg.140]

Methyl vinyl ketone can be produced by the reactions of acetone and formaldehyde to form 4-hydroxy-2-butanone, followed by dehydration to the product (267,268). Methyl vinyl ketone can also be produced by the Mannich reaction of acetone, formaldehyde, and diethylamine (269). Preparation via the oxidation of saturated alcohols or ketones such as 2-butanol and methyl ethyl ketone is also known (270), and older patents report the synthesis of methyl vinyl ketone by the hydration of vinylacetylene (271,272). [Pg.496]

Mannich reaction with pyridazinone 1-oxides takes place at the a- or y-positions relative to the iV-oxide group, in contrast to the reaction in the pyridazinone series, where N-substituted products are formed. Pyridazin-3(2FT)-one 1-oxide gives first the corresponding 6-substituted derivative with excess of the reagents, 4,6-disubstituted products are obtained. When position 6 is blocked the corresponding 4-dialkylaminomethyl derivatives are obtained. [Pg.21]

An important extension of these reactions is the Mannich reaction, in which aminomethyl-ation is achieved by the combination of formaldehyde, a secondary amine and acetic acid (Scheme 24). The intermediate immonium ion generated from formaldehyde, dimethyl-amine and acetic acid is not sufficiently reactive to aminomethylate furan, but it will form substitution products with alkylfurans. The Mannich reaction appears to be still more limited in its application to thiophene chemistry, although 2-aminomethylthiophene has been prepared by reaction of thiophene with formaldehyde and ammonium chloride. The use of A,iV-dimethyf (methylene) ammonium chloride (Me2N=CH2 CF) has been recommended for the iV,iV-dimethylaminomethylation of thiophenes (83S73). [Pg.55]

N-Unsubstituted pyrazoles and imidazoles add to unsaturated compounds in Michael reactions, for example acetylenecarboxylic esters and acrylonitrile readily form the expected addition products. Styrene oxide gives rise, for example, to 1-styrylimidazoles (76JCS(P1)545). Benzimidazole reacts with formaldehyde and secondary amines in the Mannich reaction to give 1-aminomethyl products. [Pg.54]

H,3H- Pyrrolo[l, 2-c]oxazole-l, 3-dione, 5,6,7,8-tetrahydro-IR spectra, 6, 978 [2.2](2,5)Pyrrolophane, N-aryl-rearrangements, 4, 209 Pyrrolophanes natural products, 7, 764 synthesis, 7, 771 Pyrrolophanes, N-aryl-synthesis, 7, 774 (2,4)Pyrrolophanes synthesis, 7, 771 Pyrrolo[3,4-c]pyran-4-ones synthesis, 4, 288 Pyrrolopyrans synthesis, 4, 525, 526 Pyrrolopyrazines synthesis, 4, 526 Pyrrolo[l, 2-a]pyrazines synthesis, 4, 516 Pyrrolo[2,3-6]pyrazines Mannich reaction, 4, 504 Vilsmeier reaction, 4, 505 Pyrrolo[3,4-c]pyrazole, 1,3a,6,6a-tetrahydro-structure, 6, 976 synthesis, 6, 1019 Pyrrolopyrazoles synthesis, 5, 164 Pyrrolo[l,2-6]pyrazoles synthesis, 6, 1002, 1006 Pyrrolo[3,4-c]pyrazoles reactions, 6, 1034 synthesis, 6, 989, 1043 Pyrrolo[3,4-c]pyrazolones synthesis, 6, 989 Pyrfolopyridazines synthesis, 4, 517 Pyrrolo[l, 2-6]pyridazines synthesis, 4, 297 6/7-Pyrrolo[2,3-d]pyridazines synthesis, 4, 291 2/f-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291 6/7-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291... [Pg.822]

A generally applicable reaction scheme naturally cannot be given. The reaction mechanism of one particular carbinolamine with a particular reagent can depend on the reaction conditions in nonpolar solvents, the nondissociated carbinolamine obviously reacts (Sj 2 mechanism). In polar solvents, on the other hand, the mesomeric cation reacts (S l mechanism). Formally all these reactions belong to the general class of aminomethylation. The reaction products can be considered to be Mannich bases. ... [Pg.187]

The condensation reaction of a CH-acidic compound—e.g. a ketone 3—with formaldehyde 1 and ammonia 2 is called the Mannich reaction, the reaction products 4 are called Mannich bases. The latter are versatile building blocks in organic synthesis, and of particular importance in natural products synthesis. [Pg.194]

With an unsymmetrical ketone as CH-acidic substrate, two regioisomeric products can be formed. A regioselective reaction may in such cases be achieved by employing a preformed iminium salt instead of formaldehyde and ammonia. An iminium salt reagent—the Eschenmoser salt—has also found application in Mannich reactions. ... [Pg.195]

Methyl vinyl ketone 2 tends to polymerize, especially in the presence of a strong base the yield of annulation product is therefore often low. A methyl vinyl ketone precursor, e.g. 6, is often employed, from which the Michael acceptor 2 is generated in situ, upon treatment with a base. The quaternary ammonium salt 6 can be obtained by reaction of the tertiary amine 5, which in turn is prepared from acetone, formaldehyde and diethylamine in a Mannich reaction. [Pg.241]

The Mannich reaction of polyacrylamide with formaldehyde and an amine may be used for the obtaining product that contains N-methylol groups (or ethers or ethers thereoO-... [Pg.64]

The three examples in Table 9 show Mannich reactions with 7V,A -dimethyl(methylene)im-inium salts. In the case of 5, a d.r. (exo/endo) 20 80 of the products was reported3 0. [Pg.759]


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See also in sourсe #XX -- [ Pg.488 , Pg.494 ]




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