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本文研究了在三氯化硼存在下,炔烃与二氯硼烷-甲硫醚(HCCl_2·SMe_2)的硼氢化反应。内炔烃和端炔烃与HBCl_2·SMe_2(摩尔比为1:2)在0℃反应,得到了高产率的双硼氢化产物——偕-双(二氯硼基)烷烃。在较低温度下,双硼氢化被显著地抑制。因此,在—20℃或—30℃下,内炔烃与HBCl_2·SMe_2(1.4:1)反应,定量地生成预期的烯基二氯硼烷。但在同样条件下,端炔烃既进行单硼氢化,也会经历硼氯化反应。当端炔烃在戊烷中与三氯化硼(1:1。1)反应时,高产率地得到硼氯化产物——2-氯-1-烯基二氯硼烷。各取代二氯硼烷易于醇解为相应的硼酸酯。所得化合物经IR,~1H,~(11)B,或~(13)C NMR表征。讨论了化合物的结构和它们的波谱特性之间的关系。基于化学位移,确证分子中的π-电子或孤对电子和硼原子的空ρ-轨道存在着明晰的(pp)π-相互作用。
In this paper, the hydroboration of alkyne with dichloroborane-methyl sulfide (HCCl 2 · SMe 2) was studied in the presence of boron trichloride. Internal alkynes and terminal alkynes reacted with HBCl_2 · SMe_2 (molar ratio of 1: 2) at 0 ℃, yielding bis-hydroboration product-gem -bis (dichloroboryl) alkane with high yield. At lower temperatures, bis-hydroboration is significantly inhibited. Thus, the internal alkyne reacts with HBCl 2 · SMe 2 (1.4: 1) at -20 ° C or -30 ° C to produce the desired alkenyldichloroborane quantitatively. However, under the same conditions, the terminal alkyne undergoes monohydrogenation as well as boron chlorination. When the terminal alkyne is reacted with boron trichloride (1: 1.1) in pentane, the boron chlorination product, 2-chloro-1-enyldichloroborane, is obtained in high yield. Each substituted diborane is readily alcoholysis to the corresponding boronate ester. The obtained compounds were characterized by IR, ~ 1H, ~ (11) B, or ~ (13) C NMR. The relationship between the structure of the compounds and their spectral properties is discussed. Based on chemical shifts, it is confirmed that there is a sharp (pp) π-interaction between empty ρ-orbitals of π-electrons or lone pairs of electrons and boron atoms in the molecule.