Mieczyslaw Makosza

Phase-transfer catalysis. A general green methodology in organic synthesis*

Basic concept of phase-transfer catalysis (PTC), its field of applications and specific features as the most general, efficient, and environment-friendly green methodology of organic synthesis, particularly for industrial processes, is discussed.

Reactions of organic anions—L : Reactions of phenylacetonitrile derivatives with aromatic nitrocompounds in basic media

Abstract Reaction of phenylalkanenitriles and diphenylacetonitrile with aromatic nitro compounds were studied using various base-solvent systems. Four independent types of reaction: substitution of halogen, substitution of nitro group, substitution of hydride anion and electron transfer were observed. Relationship—reaction pathway—conditions have been discussed.

Synthesis of α-Trifluoromethyl-β-lactams and Esters of β-Amino Acids via 1,3-Dipolar Cycloaddition of Nitrones to Fluoroalkenes†

Nitrones derived from aromatic or aliphatic aldehydes or ketones react with hexafluoropropene (HFP) or 2H-pentafluoropropene (PFP) to give the respective fluorinated isoxazolidine derivatives in good yields with complete regioselectivity and moderate diastereoselectivity. Catalytic hydrogenolysis of the N-O bond under ambient pressure and temperature leads to fluorides of beta-amino acids that undergo cyclization to alpha-trifluoromethylated beta-lactams or, under acidic conditions, form esters of alpha-trifluoromethylated beta-amino acids.

Vicarious nucleophilic substitution of hydrogen in nitroderivatives of five-membered heteroaromatic compounds

Abstract Nitro derivatives of thiophene, furan and pyrrole react with carbanions containing leaving groups giving products of replacement of hydrogen with functionalized alkyl substituents. Many specific features of this reaction are discussed.

σ-Complex formation and oxidative nucleophilic aromatic substitution in 4-nitro-2,1,3-benzoxadiazoles

The feasibility of carrying out nucleophilic displacement of hydrogen from highly electron-deficient heteroaromatics has been addressed through a detailed investigation of the interaction of a series of nitrobenzofuroxans 3a-i and two related heterocycles 5 and 6, with the 2-nitropropenide anion. Although this series corresponds to a large modulation in the electrophilic properties of the six-membered ring, all reactions first lead to the quantitative formation of the sigma-adducts C-3a-i, C-5 and C-6 arising from covalent addition of the nucleophile to the C-7 carbon. With the exception of the 4-aza substituted member C-5, all the adducts have been isolated as pure and very stable alkali salts. Measurements of the oxidation potentials by cyclic voltammetry reveal that the ease of subsequent hydrogen substitution at carbon-7 strongly decreases with increasing electron deficient character of the six-membered ring. The measured E0 values are in the range 0.5-0.6 V (vs. SCE) for the 4-nitro-benzofuroxan and -benzofurazan adducts (C-3e, C-3i) but they go up to 1.20-1.33 V for the 4,6-dinitro- and 4-nitro-6-trifluoromethanesulfonylbenzofuroxan adducts (C-3a,d) in acetonitrile. Consistently with these E0 values, only very powerful oxidants such as the Ce4+/Ce3+ or the MnO4-/Mn2+ couples can successfully oxidize the adducts leading to the expected substitution products in moderate to good yields (35-72%). Interestingly, the rearomatization of the 4-nitro substituted benzofuroxan adducts proceeds with a partial Boulton-Katritzky rearrangement of the resulting products. Another noteworthy result is that the 4-nitrobenzofuroxan and 4-nitrobenzofurazan molecules suffer competitive addition of the (CH3)2C-NO2- anion to the 5- and 7- positions under some experimental conditions. This represents the first well-defined example of isomeric addition of a carbon nucleophile to these heterocycles.

Vicarious substitution of hydrogen in aromatic heterocycles with carbanions of chloromethyl sulfonyl compounds

Abstract Carbanions of chloromethyl phenylsulfone and chloromethane sulfonmorpholide replace hydrogen in benzothiazole, acridine and variety of substituted 1,2,4-triazines giving corresponding sulfonyl methylderivatives.

Alkylation and the Knoevenagel Condensation of Nitrobenzylic Sulfones and Nitriles.1

Abstract Nitrobenzylic sulfones and nitriles easily available via the vicarious nucleophilic substitution of hydrogen are readily alkylated in the catalytic two-phase systems, the latter enter also the Knoevenagel condensation with aldehydes.

A novel method of indole ring system construction: One-pot synthesis of 4- and 6- nitroindole derivatives via base promoted reaction between 3-nitroaniline and ketones

Abstract Base promoted condensation of ketones RCOCH 2 R′ with 3-nitroaniline results in formation of the corresponding 4- and 6-nitro-2-R-3-R′-indoles. This multistep process apparently includes oxidative nucleophilic substitution of hydrogen in the aromatic ring of the aniline by the anotale anion and subsequent cyclization of the so formed ortho -aminoketone intermediate to indoles via a Baeyer type reaction.

Direct nitromethylation of nitronaphthalene and its heteroanalogues. A new method for functionalization of nitroarenes

Abstract Some nitroarenes react with nitromethane anion to form nitromethyl derivatives which are easily converted into corresponding nitroaromatic aldehydes.

Formation of aziridine and cyclopropane rings in reaction of quinozalines and naphthyridines with α-halocarbanions☆

Abstract Quinoxalines and 1,5-,1.6-,1.7- and 1.8-naphthyridines react easily with chloromethyl phenyl sulfone and N,N-dialkyl chloromethanesulfonamides in the presence of base to give tetracyclic bis-aziridines and cyclopropae-aziridine derivatives.