Development of Efficient Molecular Transformations Using Metal and Heteroatom Compounds

在a或β碳原子上含有phse基团的末端炔含有一些活性中心(C-C三键、酸性质子、苯基硒基团)，有可能成为合成高官能化化合物的前驱体。高炔丙基苯基硒(1)用Schwartz试剂进行氢锆化反应，得到相应的区域和立体选择性的末端乙烯基二茂锆盐。在Pd(0)催化剂的催化下，该化合物与芳基或烯基碘化物相继发生Stille型偶联反应，再经氧化脱除苯基硒，得到E构型的共轭多烯化合物。在-78℃的四氢呋喃中，苯丙基硒(2)很容易被2当量的乳酸去质子化，生成阴离子试剂的溶液。醛与二阴离子只在硒原子的a位发生反应，生成高丙醇衍生物。用1当量的m-CPBA氧化这些化合物得到…更多相应的硒氧化物，它们经过[2，3]Sigmatroic重排得到α-苯基硒取代的烯酮衍生物，推测是通过烯醇类中间体。烯酮类化合物的E-异构体通过分子内半缩合反应环合得到2-羟基-2，5-二氢呋喃衍生物。有趣的是，在反应混合物中加入吡啶导致了二氢呋喃化合物的独占形成。因此，2的双阴离子被用作丙烯醛双阴离子的合成等价物，并且这两个阴离子中心可以单独利用。类似的硅烷化炔丙基硒醚衍生物的氧化以较高的产率生成了α，β不饱和的酰基硅烷。以间丙基苯丙酸为氧化剂，合成了2-硅基-3-苯基硒呋喃化合物和γ-羟基取代的Z-α，β-不饱和酰基硅烷。前者可以通过相应的E-α，β-不饱和酰基硅烷的分子内环化和脱水得到。较少

Terminal alkynes having a PhSe group on a or β carbon atom contain some reactive sites (C-C triple bond, acidic protons, phenylseleno group) and has potential as a synthetic precursor to highly functionalized compounds. Hydrozirconation of homopropargyl phenyl selenide (1)with Schwartz's reagent gave the corresponding terminal vinylzirconocene regio-and stereoselectively. This zirconocene intermediate was successively subjected to Stille-type coupling with aryl or alkenyl iodides in the presence of Pd(0) catalyst, followed by oxidative removal of the phenylseleno group via selenoxide syn elimination to afford conjugated polyene compounds with E-configuration in good yields. Phenyl propargyl selenide (2)was easily deprotonated by 2 equiv of LDA in THF at -78℃ to give a solution of the dianion reagent. Aldehydes reacted with the dianion exclusively at the a position of selenium atom to afford homopropargyl alcohol derivatives. Oxidation of these compounds with 1 equiv of m-CPBA gave the … More corresponding selenoxides, which underwent the [2,3] sigmatropic rearrangment to yield α-phenylseleno-substituted enone derivatives, presumably via allenyl alcohol intermediates. E-isomers of enone compounds were followed by cyclization via an intramolecular hemiacetalization to give 2-hydroxy-2,5-dihydrofuran derivatives. Interestingly, the addition of pyridine to the reaction mixture led to an exclusive formation of the dihydrofuran compounds. Thus, the dianion of 2 served as a synthetic equivalent of acrolein dianion, and the two anionic centers can be utilized separately. The similar oxidation of silylated propargyl selenide derivatives resulted in the formation of α,β-unsaturated acylsilanes in good yields. Silylated homopropargyl alcohol derivatives were oxidized by m-CPBA to give 2-silyl-3-phenylselenofuran compounds and γ-hydroxy-substituted Z-α,β-unsaturated acylsilanes. The former may be obtained via an intramolecular cyclization of the corresponding E-α,β-unsaturated acylsilanes followed by the dehydration. Less