1198-01-2Relevant academic research and scientific papers
REGIO- AND STREREO-SELECTIVE SYNTHESIS OF VINYLSTANNANES. TRANSITION-METAL CATALYZED STANNYLMETALATION OF ACETYLENES AND CONVERSION OF ENOL TRIFLATES AND VINYL IODIDES INTO VINYLSTANNANES
Matsubara, Seijiro,Hibino, Jun-Ichi,Morizawa, Yoshitomi,Oshima, Koichiro,Nozaki, Hitosi
, p. 163 - 172 (2007/10/02)
Two new methods for the regio- and strereo-selective synthesis of vinylstannanes are described. (i) The reaction of terminal acetylenes with n-Bu3SnMgMe, n-Bu3SnAlEt2, or (n-Bu3Sn)2Zn in the presence of various transition-metal catalysts provides vinylstannanes in good yields.Whereas copper-catalyzed stannylmagnesation of 4-benzyloxy-1-butyne gives (E)-4-benzyloxy-1-tributylstannyl-1-butene exclusively, palladium-catalyzed stannylzincation affords 4-benzyloxy-2-tributylstannyl-1-butene preferentially. (ii) Treatment of enol triflates or vinyl iodide with Me3Sn-MgMe in the presence of CuCN catalyst gives vinylstannanes in good yields.
Hydrostannation of 1,1-bis(trimethylstannyl)ethylene and some related olefins: First steps toward constructing a karplus-type curve for 3J(Sn-Sn)
Mitchell, Terence N.,Reimann, Werner,Nettelbeck, Christa
, p. 1044 - 1048 (2008/10/08)
Four trimethylstannyl-substituted alkenes, Me3SnCR=CH2 (R = Ph, t-Bu, Me3Si, Me3Sn), were hydrostannated by trimethyltin hydride. Though all four olefins reacted, that with R = t-Bu was consumed only very slowly. The major product was, as expected, the 1,2-distannylalkane RCHSnMe3CH2SnMe3; however, for R = Me3Sn 40% of the regioisomer (Me3Sn)2CRCH3 was obtained compared with at most 5% in the other cases. On the basis of NMR data (1H, 13C, 29Si, 119Sn) for distannylalkanes and for Me3SnCH2CH2SiMe3 the preferred rotamers in solution (CDCl3) at room temperature have been determined. The value of 3J(Sn-Sn) corresponding to a dihedral angle of 180° is ca. 1100 Hz, while an angle of 90° apparently corresponds to a value near zero: values of this magnitude are shown by allene-hexamethylditin adducts. First results on bromodemethylated derivatives show that the effect of increasing the electronegativity of the tin moiety is not straightforward.
