Rifkat M. Sultanov

CATALYTIC SYNTHESIS AND REACTIONS OF MAGNESIOCYCLOALKANES. 2.* SYNTHESIS OF SUBSTITUTED MAGNESIOCYCLOPENTANES IN THE PRESENCE OF ZIRCONIUM COMPLEXES

Catalytic cyclometallation of styrene,m-methylstyrene,p-tert-butylstyrene, and 1-hexene with di-n-alkylmagnesium compounds (n-R2Mg, where R=C3H7, C4H9, and C6H13) in the presence of Cp2Zr2Cl2 has given high yields of 2,4-disubstituted magnesiocyclopentanes. The probable mode of formation of magnesiocyclopentanes, involving zirconocyclopentanes formed from Cp2ZrCl2,n-R2Mg, and the appropriate olefins as reactive intermediates in the cyclometallation, is discussed.

Catalytic synthesis and transformations of magnesium-cycloalkanes. 1. New catalytic transformations in the series of magnesium-cyclopentanes

The reactions of magnesium-cyclopentane with styrene and of 2,4-diphenylmagnesium-cyclopentane with ethylene in the presence of catalytic amounts of Cp2-ZrCl2 leading to the formation of 2-phenylmagnesium-cyclopentane and 2,4-di-phenylmagnesium-cycloheptane, were studied for the first time. It was found that zirconocyclopentanes, are intermediates in this reaction, which are formed both from magnesium-cycloalkanes and from α-olefins and Cp2ZrCl2. A possible mechanism of the reactions studied has been proposed.

Bu2iAlCl-Cp2TiCl2 — A new reagent for hydroalumination of disubstituted acetylenes

A new regio- and stereoselective method for the synthesis ofE-alkenylchloralanes based on Cp2TiCl2-catalyzed hydroalumination of disubstituted acetylenes by diisobutylaluminum chloride was developed. Hydrolysis and deuterolysis of organoaluminum compounds lead to the correspondingZ-olefins, and cross-coupling with ally) halides in the presence of Pd(Ph3P)4 results in the formation ofcis-4,5-disubstituted 1,4-dienes.

One-Step Synthesis of Racemic 4-Methyloctanoic Acid, a Component of the Aggregation Pheromone of Oryctes rhinoceros

The principal constituents of the pheromone of male rhinoceros beetles of the genus Oryctes are 4-methyloctanoic acid (1) and its ethyl ester [1]. Known methods for synthesizing racemic 1 are typically multi-step and in most instances use difficultly accessible compounds as starting materials [2, 3–6]. We developed a convenient and efficient synthetic pathway to 1 that was based on the catalytic carbomagnesiation of 1-alkenes using EtMgCl (Et2Mg) and TaCl5 catalyst that was recently discovered by us (Scheme 1) [7].

One-Step Synthesis of Racemic 6-Methyloctan-3-One, an Alarm Pheromone Component of Ants of the Genus Crematogaster

6-Methyloctan-3-one (1) was identified as a component of the alarm pheromone of ants of the genus Crematogaster [1]. Several syntheses of this compound as the racemate and an enantiomer are known [2–6]. However, many of them involve several steps and most are labor-intensive and require costly starting materials. We developed a convenient and effective synthetic pathway for a racemic analog of 1 that was based on our recently proposed regioselective carbonylation of 1-alkenes using Et2Zn and TaCl5 catalyst [7]. The reaction of but-1-ene with Et2Zn in the presence of TaCl5 (Et2Zn–but-1-ene–TaCl5 = 110:100:5; Et2Zn concentration 1.0 mmol/mL in hexane, 20°C, 5 h) formed organozinc compound 2. For this, hexane (20 mL) was cooled to –15°C and treated with but-1-ene (2.25 ml, 20 mmol) cooled to –30°C. Then, the solution was cooled to –15–20°C, treated with Et2Zn (2.25 mL, 22 mmol) and TaCl5 (0.4 g, 1 mmol), heated gradually to room temperature, stirred for 5 h, cooled to –5°C, and treated dropwise with propionylchloride (3, 1.74 mL, 20 mmol) in hexane. All these operations were performed under a dry Ar atmosphere. The resulting reaction mixture was stirred for 2 h and treated with aqueous HCl solution (10%). The resulting 1 was extracted by Et2O (3 50 mL). The extracts were dried over anhydrous MgSO4. The solvent was distilled off. The residue was chromatographed (SiO2, hexane) to afford 1 (2.69 g, 99% pure) in 95% yield based on 3 (Scheme 1). The structure of 1 was proven using IR, PMR, and 13C NMR spectral methods and GC-MS in addition to comparison with an authentic sample [6].