34602-23-8Relevant academic research and scientific papers
Nickel-Catalyzed Cross-Coupling Reaction of Allyl Halides with Alkynyltins
Cui, Dong-Mei,Hashimoto, Naoko,Ikeda, Shin-ichi,Sato, Yoshiro
, p. 5752 - 5756 (1995)
A cross-coupling reaction of allyl halides 1 with alkynyltins 3 in the presence of "Ni(PR3)n" (R = Ph, OEt, or OPh) catalyst was carried out in THF at reflux to give 1,4-enynes.The regioselectivity of the coupling of 1f-i with 3a was investigated in the presence of various phosphorus ligands.Interestingly, prenyl (1j) and geranyl chlorides (1k) selectively reacted with 3 at the more-hindered positions of substituted η3-allylnickel intermediates 21 (M = Ni) to yield 23 and 25, respectively.Regioselectivity in these reactions may result from greater steric crowding between the phosphorus ligand and the disubstituted position in 26b than in 26a.In contrast, the palladium-catalyzed reactions of 1j and 1k with 3 selectively gave 22 and 24, respectively.Thus, the steric crowding in a Pd analogue of 26b is less than that in a Ni analogue of 26b, since Pd has a larger covalent radius than Ni.
