Thienyl- stannanes

Besides halopyridazines, pseudohalopyridazines have been used as substrates for Stille reactions [29]. 6-Methylpyridazin-3-yl trifluoromethanesulfonate (96) reacted with arylstannanes using a procedure based on Stille s original conditions for aryl triflates. Although 3-methyl-6-(2-thienyl)pyridazine was obtained in a good yield (77%) under these conditions, trialkyl(phenyl)stannanes reacted only very slowly in comparison with tributyl(2-thienyl)stannane. Trimethyl(phenyl)stannane and tributyl (phenyl) stannane gave 3-methyl-6-phenylpyridazine in only 22 and 6% yield, respectively. 

Tetra-2-thienylstannane, loci Tetrakis(2-thienyl)stannane [23290-53-1]... 

Acylation, vinylation, and ethinylation involving Pd(0)-catalyzed coupling reactions can be performed with halothiophenes, thiophene boronic acids, or thienyl stannanes following the classical Suzuki-Miyaura, Stille, or Sonogashira protocols [64]. 

Compound 129, an intensely blue compound, was obtained by direct functionalization of DDTOMe 20b with LDA and chloro(chloromethyldimethylsilane) at one of the terminal positions followed by conversion of chloride to NCS using sodium thiocyanate in acetone (Scheme 12). The other isothiocyanates were prepared via Stille coupling of mono or dibrominated rigid cores with appropriate thienyl or phenyl stannanes followed by conversion of the chlorine atom of Si(CH3)2CH2Cl attached to a phenyl group into isothiocyanate occurred in rather low yield. 

Thienyl- and 3-thienyl-(tributyl)stannanes react with chlorosulfonyl isocyanate at 20°C to give the corresponding sulfonyl isocyanates by ipso-substitution (Scheme 78). The yields are > 90% (93JOC7022). 

Barbarella, G. Zambianchi, M. Polyhydroxyl oligofhiophenes. I. Regioselective synthesis of 3,4 - and 3,3 -di(2-hydroxyefhyl)-2,2 -bifhio-phene via Pd catalyzed coupling of fhienyl-stannanes with thienyl bromides. Tetrahedron 1994, 50,11249-11256. 

Coupling of the (erf-butyl ether of 5-bromouracil (125) with N-methylpyrrol-2-yl(trimethyl)stannane gave the expected product (126) in low yield (Scheme 27). Modest yields of coupling products (127) were also obtained in reactions with 2-thienyl- and 2-selenylstannanes and unprotected iodouracil. With the pyridylstannane only the 3-isomer showed some reactivity. Silylation of 5-bromouracil is recommended before the coupling reaction. Silyl-protected uracil (128) reacts with formation of a number of biheteroaryl derivatives (129) including pyridylstannanes, except for the 4-isomer (90JHC2165). 

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