Synthesis of Polyfunctionalyzed Molecules Using Cooperative Interactions between Multiple Elements

末端炔(1)在α或β碳原子上有一个PhSe基团，含有三个反应位点（C-C三键，末端炔氢原子，PhSe基团）。一般来说，末端炔的金属氢化反应是立体定向的，产生e -烯基金属，这些金属被一些亲电试剂如醛类、环氧化物和酰基卤化物取代，从而形成新的碳-碳键。另一方面，近年来有机硒化学成为有机合成的有力工具。特别重要的是由于其易于处理的性质。1与锆茂烯-乙烯络合物反应得到区域选择性锆环戊烯衍生物。1与Cp_2ZrHCl氢化锆，再与Me_2Zn转金属，得到相应的末端乙烯基锌中间体，该中间体与醛进行偶联反应，得到具有苯基硒基的烯丙醇衍生物。1的末端氢原子在78℃时被n-BuLi萃取，生成sp种碳离子，这些碳离子被环氧化合物上的醛类有效捕获。将含苯硒基的化合物用过量的H_2O_2氧化，经硒酸盐合成消除，得到收率高的a型烯烃部分。苯基硒酸酯与二甲基二茂钛（Cp_2TiMe_2）发生甲基化反应，得到烯基硒化物，并与m-CPBA氧化生成端炔，而非烯烯。另一方面，α-苯基硒酮与Cp_2TiMe_2反应生成异构的烯丙基硒化物，H_2O_2氧化生成烯丙基醇[2,3]。

Terminal alkynes (1) having a PhSe group on α or β carbonn atom contain three reactive sites (C-C triple bond, terminal alkynic hydrogen atom, PhSe group). Generally, hydrometalation of terminal alkynes takes place stereospecifically to give the E-alkenic metal species which are replaced by some electrophiles such as aldehydes, epoxides, and acyl halides to construct a new carbon-carbon bond. On the other hand, organoselenium chemistry became a very powerful tool in organic synthesis in recent times. Of particular importance is the owing to its easily handled nature.1 reacted with zirconocene-ethylene complex to give regioselectively zirconacyclopentene derivatives. Hydrozirconation of 1 with Cp_2ZrHCl followed by transmetalation with Me_2Zn gave the corresponding terminal vinylzinc intermediates regio-and stereoselectively, which underwent the coupling reaction with aldehydes to afford the allylic alcohol derivatives having a phenylseleno group. Terminal hydrogen atom of 1 was easily abstracted by n-BuLi at-78℃ to generate sp carbanion species which were effectively trapped by aldehydes on epoxides. The compounds with a phenylseleno group were oxidized with excess amounts of H_2O_2 to yield the desired products having A-shaped olefinic alcohol moiety in good yields via selenoxide syn elimination.Methylenation of phenylselenolesters with dimethyl titanocene (Cp_2TiMe_2) gave alkenyl selenides, which were subjected to oxidation with m-CPBA to afford terminal alkynes, not to allene, via selenoxide syn elimination. On the other hand, reaction of α-phenylseleno ketones with Cp_2TiMe_2 gave a mixture of isomeric allylic selenides and the subsequent oxidation by H_2O_2 led to the formation of allylic alcohols via [2,3] sigmatropic rearrangement.