- Organocatalytic Chlorination of Alcohols by P(III)/P(V) Redox Cycling
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A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.
- Longwitz, Lars,Jopp, Stefan,Werner, Thomas
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p. 7863 - 7870
(2019/06/27)
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- 2-[2-(4-Methoxyphenyltelluro)ethyl]thiophene (L1) bis[2-(2-thienyl)ethyl] telluride (L2) and their metal complexes; crystal structure of trans-dichlorobis{2-(2- (4-methoxyphenyltelluro)ethyl)thiophene-Te}palladium(II) and {bis[2-(2-thienyl)ethyl] telluride}dichloro(p-cymene)ruthenium(II)
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The reaction of ArTe- (Ar=4-MeOC6H4) and Te2- generated in situ by borohydride reduction of Ar2Te2 and Te, respectively, with 2-(2-thienyl) ethyl chloride has resulted in 2-[2-(4-methoxyphenyltelluro) ethyl]thiophene (L1) and bis[2-(2-thienyl)ethyl] telluride (L2), respectively. Their complexes [AgNO3 (L1)] (1) [PdCl2(L1)2] (2) [PtCl2(L1)2] (3) [HgBr2 (L1)]2 (4) [Ru(p-cymene)Cl2 (L1)] (5) [Ru(p-cymene)Cl2(L2)] (6) and [PdCl2(L2)2] have been synthesized. The ligands and complexes exhibit characteristic 1H and 13C{1H} NMR spectra. Both the ligands coordinate only through Te in all the complexes. The single crystals of 2 and 6 are characterized by X-ray diffraction. Compound 2 has square planar geometry around Pd and trans arrangement of ligands. The Pd-Te bond distances 2.5951(7) and 2.5872(7) ? are longer than the values expected due to strong trans influence. The unique intermolecular secondary Te?Cl interaction (distance=3.450/3.449 ?) between neighbouring molecules has been observed in the crystal structure of 2. The distance between Pd atoms of two neighbouring molecules 3.2143(10) ? has also been found less than the sum of van der Waal's radii 3.26 ?. These secondary interactions in 2 result in the formation of a dimeric species, which remains intact even in the solution. Compound 6 is a half sandwich having three coordination sites occupied by two Cl atoms and the Te atom of L2 with Ru-Te bond distance of 2.6528(9) ? and Ru-Cl, 2.415(2)/2.422(2) ?.
- Bali, Sumit,Singh, Ajai K.,Sharma, Pankaj,Toscano,Drake,Hursthouse,Light
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p. 2346 - 2353
(2007/10/03)
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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