Mieczysław Ma̧kosza

Synthesis of 1-hydroxyindoles and indoles from ortho-nitroarylethanes

Cyclization of substituted ortho-nitroarylethanes to 1-hydroxyindoles and their further reduction to indoles is described. The mechanism of cyclization is discussed.

Vicarious nucleophilic substitution of hydrogen in pyridazines

Abstract Pyridazines, 3-pyridazinones and 3,6-pyridazinediones readily undergo vicarious nucleophilic substitution of hydrogen (VNS) with carbanion of chloromethyl p-tolyl sulfone to form new carbon-carbon bonds. The reaction offers a novel approach to the synthesis of functionalized pyridazine derivatives.

Synthesis of α-(Nitroaryl)benzylphosphonates via Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes†

Carbanions of diethyl benzylphosphonate and diethyl 1-phenylethylphosphonate add to nitroarenes to form relatively long-lived sigma(H) adducts that can be oxidized to products of oxidative nucleophilic substitution of hydrogen. By variation of the conditions, o- and p-nitroarylated derivatives of the starting phosphonates can be synthesized regioselectively. It has been proven that addition of carbanions of diethyl benzylphosphonate and diethyl 1-phenylethylphosphonate to nitroarenes is a fast process and the respective sigma(H) adducts are formed almost quantitatively.

Oxidative nucleophilic substitution of hydrogen in nitroarenes with phenylacetonitrile derivatives

Abstract Tertiary carbanions generated from α-substituted phenylacetonitriles in liquid ammonia add to nitro-benzenes in the para position to form the corresponding σH-adducts which are transformed, depending on the starting nitriles and the reaction conditions, to products of oxidative nucleophilic substitution of hydrogen, ONSH or vicarious nucleophilic substitution, VNS.

Cocatalysis in phase-transfer catalyzed β-elimination reactions

Abstract The phase-transfer catalyzed β-elimination of HBr from alkyl bromides with aqueous NaOH in two-phase systems proceeds efficiently when tetraalkylammonium salts and weak HO- or HN-acids are used as the catalysts. The latter continuously produce basic, moderately nucleophilic, lipophilic anions, which in the form of tetraalkylammonium salts afford the elimination in the organic phase.

Convenient preparation of metals deposited on solid supports and their use in organic synthesis

Abstract “High-surface alkali metals” can be conveniently prepared via deposition of corresponding metals on various supports such as sodium chloride, polyethylene, polypropylene and cross-linked polystyrene from their solutions in liquid ammonia. Alkali metals deposited on polymeric supports can be stored in form of stable suspensions in inert solvents and used for the acyloin and Dieckmann condensations and for preparation of organolithiums. Addition of the suspension of supported alkali metal to a solution of zinc chloride gave an active zinc on polymeric support, which can be used for the Reformatski and Barbier reactions.

Synthesis of 1,3,4,5-tetrahydropyrrolo-[4,3,2-de]quinolines via the vicarious nucleophilic sybstitution of hydrogen

Abstract The VNS reaction was used as key steps in synthesis of O-methylnordehydrobufotenine and its 8-methoxy isomer starting from simple benzene derivatives. Attempts to use nitrobenzoxazole derivatives as a starting material were made. Several approaches were developed but all of them failed to produce the desired ring system on various stages of synthesis.

Vicarious nucleophilic substitution of hydrogen in nitrophenyl toluenesulfonates

Abstract Toluenesulfonates of nitrophenols react with carbanions possessing leaving groups giving products of the vicarious nucleophilic substitution of hydrogen. The yields and orientation depend on the reaction conditions and the structure of the reagents. The products obtained can be easily hydrolyzed to the corresponding phenols or — in certain cases — to hydroxynitrobenzaldehydes.

The vicarious nucleophilic substitution of hydrogen and related reactions in nitrobenzoxazoles

Abstract 5- and 6-nitrobenzoxazoles 3 and 4 react with nucleophiles exclusively at C-2, giving ring opening products. If position 2- is blocked with phenyl substituent the reaction takes place in the carbocyclic ring affording the VNS products. 2-Methylthio-5-nitrobenzoxazole 7 and its 6-nitro isomer 8 give products which result from addition of a nucleophile to the carbocyclic ring (VNS) as well as to the heterocyclic ring (SNAr and ring cleavage). 2-Methylthiobenzoxazoles can be readily converted to the corresponding benzoxazolones via oxidative hydrolysis.

Vicarious nucleophilic substitution of hydrogen proceeding via heterocyclic ring opening

Abstract Carbanions of five-membered S -heterocycles react with nitroarenes via the ring-opening VNS reaction or oxidative nucleophilic substitution of hydrogen. The reaction course is affected by rigidity of the ring.