3- Thienylmagnesium bromide

Thiopyran 134a (R = 2-thienyl) was prepared from perchlorate 135 (R = H) with 2-thienylmagnesium bromide (91KGS900). 

The procedure described is essentially that of Lawesson and Frisell.4 2-Hydroxythiophene has been prepared in low yields by Hurd and Kreuz 5 from 2-thienylmagnesium bromide and oxygen in the presence of excess isopropylmagnesium bromide. 

In a similar sequence, reaction of ketoester 52 with 2-thienylmagnesium bromide gives a modest yield of the benzilic ester 53. Transesterification of this with aminoalcohol 51, prepared analogously to 45 by starting with methylamine, gives, after quaternization with methyl bromide, heteronium bromide... 

Advantage has been taken of the aforementioned observations in the synthesis of a terthiophene natural product, arctic acid (147) [123]. Pd-catalyzed carbonylation of bromobisthiophene 25, obtained from the Kumada coupling of 2-thienylmagnesium bromide and 2,5-dibromothiophene, gave bithiophene ester 144, which was converted to iodide 145 by reaction with iodine and yellow mercuric oxide. Subsequent propynylation of 145 was then realized using the Sonogashira reaction with prop-l-yne to give bisthienyl alkyne 146, which was subsequently hydrolyzed to 5 -(l-propynyl)-2,2 -bithienyl-5-carboxylic acid (147), a natural product isolated from the root of Arctium lappa. 

Rossi and associates described a Kumada coupling of 2-bromofuran with 2-thienylmagnesium bromide to assemble thienylfuran 11 [19], The reaction proceeded readily at room temperature. 

Thienol was prepared and characterized by Hurd and coworkers (38). It was obtained by oxidation of 2-thienylmagnesium bromide. Its behavior indicated the existence of a thiolactone form (tautomeric form) ... 

Vinylthiophene has been prepared by the dehydration of a-(2-thienyl)ethanol,3-6 by the condensation of vinyl chloride with 2-thienylmagnesium bromide in the presence of cobaltous chloride,6 and by the dehydrochlorination of cc-(2-thienyl) ethyl chloride.7... 

Table 47 Chemioal shifts in NMR speotra of 2-lithiothiophene 79, 2-thienylmagnesium bromide 80, di(2-thienyl)magne-sium 81, 2-trimethylsilylthiophene 82, and 2-f-butoxythiophene 88...

Thienylmagnesium bromide is reported to undergo an exothermic coupling reaction with 3,6-dichloropyridazine in the presence of catalytic bis(l,3-diphenylphosphino)propane nickel(II) to give... 

The preparation of 2-thienylcerium reagent has been referred to in Section 2.10.4.7.1. This reagent reacts with spirodiketones to form the corresponding alcohols <91CC1614>. Apparently 2-thienyllithium fails in this reaction, but excess 2-thienylmagnesium bromide can be used instead of the cerium reagent. 

Several tricyclic monomers required for oxidative (electrochemical or chemical) polymerization have been prepared by coupling reactions. Thus, l,4-diiodo-2,5-dimethylbenzene was coupled with 2-thienylmagnesium bromide in the presence of nickel(II) bis(diphenylphosphino)propane dibromide (NidpppBr2). However when methoxy groups were present in the benzene ring ortho to the site of coupling, the decreased electrophilicity necessitated the use of a more nucleophilic thiophene derivative, 2-thienylcopper (Equation (60)). 

Miller el al. prepared tris[4-(2-thienyl)phenyl] amine 5.18a by Pd°-catalyzed coupling of 2-thienylmagnesium bromide with tris(4-bromophenyl)amine in 79% yield (Chart 1.65) [467]. Yamamoto et al. [468] synthesized an analogous bithiophene derivative 5.18b by bromination of... 

Fluorination of hexafluoro-l,3-bis-(2-thenoyl)propane (best prepared by treatment of perfluoroglutaric acid with a large excess of 2-thienylmagnesium bromide) with sulphur tetrafluoride yields the decafluoro-compound (86) and a small amount of material that might be the tetrahydropyran derivative (87). ... 

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