4104-90-9Relevant articles and documents
Wurtz-type reductive coupling reaction of allyl bromides and haloorganotins in cosolvent/H2O(NH4Cl)/Zn media as a route to allylstannanes and hexaaryldistannanes
Von Gyldenfeldt, Friederike,Marton, Daniele,Tagliavini, Giuseppe
, p. 906 - 913 (2008/10/08)
Twenty-one allylstannanes have been prepared via a simple Wurtz-type coupling reaction of allyl bromides and R3SnX compounds (R = Me, Et, Pr, Bu, Ph; X = Cl, I, OH), Bu2SnCl2, and (Bu2SnCl)2O in cosolvent/H2O (NH4Cl saturated) media under the mediation of zinc powder. Also R3SnSnR3 compounds (R = Ph, p- and m-Tol) have been prepared via coupling of triaryltin chlorides. The stereochemical course of the reaction between R3SnCl and (C4H7)Br (C4H7 = α-methylallyl, trans- and cis-crotyl) has been extensively studied. Two distinct reactions are involved in the overall process: (i) the coupling reaction, which gives rise stereoselectively to the sole R3SnCH(CH3)CH=CH2 (α-isomer), and (ii) the subsequent isomerization of the α-isomer furnishing mixtures of (α, trans, cis)-isomers. The occurrence of reaction ii depends upon the nature either of the R group or the employed cosolvent. In cyclohexane, the α-isomer is exclusively obtained with R = Bu, while with R = Me, Et, and Pr it is found as a major component in the ternary isomeric mixture. In tetrahydrofuran, 2-propanol, acetonitrile, and pyridine, the isomerization occurs to an extent which depends on the polarity and the coordinating ability of the cosolvent itself. The observed stereoselection has been hypothesized to occur through one-electron transfer from the zinc metal to the (C4H7)Br to form stereoselectively an adsorbed CH2=CHCH(CH3)Br?-Zn?+ radical ion which is trapped by the R3SnCl reactant to form the α-isomer. Similarly, ditin compounds are thought to be formed by interaction of R3SnCl?-Zn?+ radical ions with R3SnCl molecules.
Free-Radical Chain Substitution Reactions (SH2') of Alkenyl-, Alkynyl-, and (Alkenyloxy)stannanes
Russell, Glen A.,Herold, Lourdes Lucas
, p. 1037 - 1040 (2007/10/02)
Free-radical chain substitution reactions of allyltributylstannane were observed with PhSSPh, PhCH2SSCH2Ph, PhSeSePh, PhSO2Cl, n-PrSO2Cl, or CCl3SO2Cl, where the attacking radicals leading to allylic rearrangement with displacement of Bu3Sn(radical) were PhS(radical), PhCH2S(radical), PhSe(radical), PhSO2(radical), n-PrSO2(radical), and CCl3(radical), respectively.Allylic rearrangement was also observed in the SH2' reaction of crotyltributylstannane with PhSSPh, PhCH2SSCH2Ph, PhSO2Cl, or n-PrSO2Cl.Propargyltriphenylstannane underwent SH2' substitution to form the allenic substitution products with PhSO2Cl, n-PrSO2Cl, CCl4, and CHCl3 while 2-butynyltriphenylstannane formed the 1,2-butadiene with PhSO2Cl or n-PrSO2Cl.Reaction of (1-cyclohexenyloxy)tributylstannane with CCl4 or BrCCl3 formed α-(trichloromethyl)cyclohexanone.With HCBr3 the initially formed α-(dibromomethyl)cyclohexanone readily underwent dehydrobromination to form α-(bromomethylene)cyclohexanone. tributylstannane formed α-(trichloromethyl)isobutyraldehyde with CCl4 or BrCCl3.Reaction with HCBr3 gave a mixture of α-(dibromomethyl)isobutyraldehyde and 1-(dibromomethyl)-2,2-dimethyloxirane.
REGIO- AND STEREO-CHEMICAL FEATURES OF THE STANNYLCOPPER(I)-INDUCED SUBSTITUTION IN PROPARGYLIC SUBSTRATES
Ruitenberg, K.,Westmijze, H.,Meijer, J.,Elsevier, C. J.,Vermeer, P.
, p. 417 - 422 (2007/10/02)
Stannylcopper(I) species, R3SnCu and 2CuLi, preferentially convert propargylic substrates, R1CCCR2R3X (X=Br, MeCO2, MeS(O)O or MeSO3) into allenes R3Sn(R1)C=C=CR2R3.Only when the group R1 causes much greater steric hindrance than with R2 and R3 is the acetylenic product R1CCCR2R3SnR3 formed.The stereochemical course of the allene formation has been studied in both the steroid and non-steroid series, and found to be mainly or exclusively anti.
