Selective Phenol Alkylation: An Improved Preparation of Efaproxiral

An improved, two‐step synthesis of efaproxiral, used in breast cancer therapy, is described, utilizing inexpensive commodity chemicals for starting materials. Selective amide formation and O‐alkylation in the presence of multireactive functional groups is demonstrated, thus avoiding protection/deprotection steps.     

己内酰胺一步法氢化烷基化合成N-烷基环己亚胺

A new synthetic method for the preparation of N-alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic alkylation of caprolactam with alcohol and then directly hydrogenated into N-alkylhexahydroazepine over Cu-ZnO/γ-Al2O3 catalyst.     

The Allylic Alkylation of Ketone Enolates

The palladium-catalyzed allylic alkylation of non-stabilized ketone enolates was thought for a long time to be not as efficient as the analogous reactions of stabilized enolates, e. g. of malonates and β-ketoesters. The field has experienced a rapid development during the last two decades, with a range of new, highly efficient protocols evolved. In this review, the early developments as well as current methods and applications of palladium-catalyzed ketone enolate allylations will be discussed.     

Studies of Birch Reductive Alkylation of Substituted α-Tetralones

A series of α-tetralones, with different degree of substitution, was submitted to the Birch reduction-alkylation procedure using various alkylating agents, to produce angularly substituted 1,4-unsaturated decalones. The stereoselectivity behavior of such dienones upon reduction is also described.     

S‐Alkylation of Soft Scorpionates

The alkylation reactions of soft scorpionates are reported. The hydrotris(S‐alkyl‐methimazolyl)borate dications (alkyl=methyl, allyl, benzyl), which were prepared by the reaction of Tm^Me anion and primary alkyl halides, have been isolated and structurally characterised. The reaction is, however, not universally successful. DFT analysis of these alkylation reactions (C?S versus B? H alkylation) indicates that the observed outcome is driven by kinetic factors. Extending the study to incorporate alternative imine thiones (mercaptobenzothiazole, bz; thiazoline, tz) led to the structural characterisation of di[aquo‐μ‐aquohydrotris(mercaptobenzothiazolyl)boratosodium], which contains sodium atoms in the κ³‐S,S,S coordination mode. Alkylation of Na[Tbz] and Na[tzTtz] leads to decomposition resulting in the formation of the simple S‐alkylated heterocycles. The analysis of the species involved in these reactions shows an inherent weakness in the B? N bond in soft scorpionates, which has implications for their use in more advanced chemistry.     

Cobalt‐Catalyzed Alkylation of Aromatic Amines by Alcohols

The implementation of inexpensive, Earth‐abundant metals in typical noble‐metal‐mediated chemistry is a major goal in homogeneous catalysis. A sustainable or green reaction that has received a lot of attention in recent years and is preferentially catalyzed by Ir or Ru complexes is the alkylation of amines by alcohols. It is based on the borrowing hydrogen or hydrogen autotransfer concept. Herein, we report on the Co‐catalyzed alkylation of aromatic amines by alcohols. The reaction proceeds under mild conditions, and selectively generates monoalkylated amines. The observed selectivity allows the synthesis of unsymmetrically substituted diamines. A novel Co complex stabilized by a PN₅P ligand catalyzes the reactions most efficiently.     

Alkylation of Phosphorylmethylenetriphenylphosphoranes

Abstract

Direction of alkylation of phosphoranes (I) depends on the nature of the substituent Y and the alkylating agent. Unsubstituted phosphorane reacts with CH₃J yielding only the product of C-methylation (II), whereas the reaction with Me₂SO₄ proceeds at both ends of the OPC-triad, preferably yielding the O-alkylation product (IIIa, 80%).     

Alkylation of dihydrofullerenes

The fulleride dianions C(60)(2-) and C(70)(2-) were generated by deprotonation of the corresponding hydrogenated fullerenes, 1,2-C(60)H(2) and 1,2-C(70)H(2). These anions were prepared in the presence of a variety of alkylating agents, and mono- or dialkylated products were obtained. Alkylation was not successful with sulfonate ester alkylating agents. Deprotonation of monoalkylated compounds, followed by second alkylation with a different alkylating agent, produced heterodialkylated compounds. The monoalkyated material was invariably the 1,2-isomers, while the dialkylated materials were generally 1,4-isomers, although some 1,2-isomer was observed in the C(70) context. The major product from alkylation of C(70)(2-) was the 7,23-isomer 13a, a structure where the alkylation took place near the equator of the fullerene cage, rather than at the more strained carbons near the poles.     

Alkylation of aminothiazoles

2-Alkylamino-4-ethylthiazoles were obtained by the alkylation of 2-amino-4-ethylthiazole with secondary alcohols, while 2-amino-4-ethyl-5-tert-butylthiazole was obtained by the reaction of the thiazole with tert-butyl alcohol.     

Liquid Phase Friedel‐Crafts Alkylation over Mixed Metal Oxide Catalyst

Liquid phase Friedel‐Crafts alkylation of benzene with benzyl chloride was carried out over various ferrites viz. CuFe₂O₄, NiFe₂O₄, CoFe₂O₄, ZnFe₂O₄, and MgFe₂O₄. Among the various ferrites ZnFe₂O₄ showed the highest activity. These ferrites were prepared by co‐precipitation technique. The effect of variation of catalyst, speed of agitation and reaction temperature has been studied. Benzylation of other substrates such as toluene, anisole and chlorobenzene was also studied. The catalyst ZnFe₂O₄ was found to be reusable. The acid base properties of the catalyst were studied by cyclohexanol dehydration reaction and the data was correlated with activity.     

Catalytic Intramolecular Ketone Alkylation with Olefins by Dual Activation

Two complementary methods for catalytic intramolecular ketone alkylation reactions with unactivated olefins, resulting in Conia‐ene‐type reactions, are reported. The transformations are enabled by dual activation of both the ketone and the olefin and are atom‐economical as stoichiometric oxidants or reductants are not required. Assisted by Kool’s aniline catalyst, the reaction conditions can be both pH‐ and redox‐neutral. A broad range of functional groups are thus tolerated. Whereas the rhodium catalysts are effective for the formation of five‐membered rings, a ruthenium‐based system that affords the six‐membered ring products was also developed.     

Alkylation of aminothiazoles

Alkylation of 2-ethylamino-4-methylthiazole with isopropanol and tert-butanol in 85% H₂SO₄ gave 2-ethylamino-4-methyl-5-alkylthiazoles. The structure of the resultant compounds is shown by lack of diazo coupling and formation of p-chlorobenzenesulfonyl derivatives.For Part IV see [1].     

Alkylation of aminothiazoles

The alkylation of 2-aminothiazole and 2-amino-4-methylthiazole with ten-butyl alcohol in sulfuric acid has been repeated. In correction of preceding information, it has been found that alkylation takes place in position 5 of the thiazole ring and not at the amino group. The presence of a primary amino group in the alkylation products was shown by the production of arylsulfonyl derivatives soluble in alkalies and of 2-halothiazoles by the Sandmeyer replacement of the amino group by halogen. Alkylation with alkyl halides yielded the corresponding thiazolone imides.For part VI, see [6].     

Alkylation of indoles

Reaction of indole with tert-butyl chloride in the presence of zinc chloride or acetate gives 3-tert-butylindole, with 1,3-di-tert-butylindole as a by-product.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 620–621, May, 1970.