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首页> 外文期刊>Chemistry: A European journal >Six-and Eightfold Palladium-Catalyzed Cross-Coupling Reactions of Hexa-and Octabromoarenes
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Six-and Eightfold Palladium-Catalyzed Cross-Coupling Reactions of Hexa-and Octabromoarenes

机译：六和八溴芳烃的六和八倍钯催化的交叉偶联反应

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Palladium-catalyzed sixfold coupling of hexabromobenzene(20)with a variety of alkenylboronates and alkenylstannanes provided hexaalke-nylbenzenes 1 in up to 73% and 16 to 41 % yields,respectively.In some cases pentaalkenylbenzenes 21 were isolated as the main products(up to 75%).Some functionally substituted hexaal-kenylbenzene derivatives containing oxygen or sulfur atoms in each of their six arms have also been prepared(16 to 24% yield).The sixfold coupling of the less sterically encumbered 2,3,6,7,10,11-hexabromotriphenylene(24)gave the desired hexakis(3,3-di-methyl-l-butenyl)triphenylene(25)in 93% yield.The first successful cross-coupling reaction of octabromonaph-thalene(26)gave octakis-(3,3-dimeth-yl-l-butenyl)naphthalene(27)in 21% yield.Crystal structure analyses disclose that,depending on the nature of the substituents,the six arms are positioned either all on the same side of the central benzene ring as in la and li,making them nicely cup-shaped molecules,or alternatingly above and below the central plane as in Ih and 23.In 27,the four arms at C-1,4,6,7 are down,while the others are up,or vice versa.Upon catalytic hydrogenation,la yielded 89% of hexakis(terf-butyl-ethyl)benzene(23).Some efficient accesses to alkynes with sterically demanding substituents are also described.Elimination of phosphoric acid from the enol phosphate derived from the corresponding methyl ketones gave 1-ethynyladamantane(3b,62% yield),1-ethynyl-l-methylcyclohexane(3c,85%)and 3,3-dimethylpentyne(3e,65 %).l-(Trimethylsilyl)ethynylcyclo-propane(7)was used to prepare 1-eth-ynyl-1-methylcyclopropane(3d)(two steps,64% overall yield).The functionally substituted alkynes 3 f-h were synthesized in multistep sequences starting from the propargyl chloride 11,which was prepared in high yields from the dimethylpropargyl alcohol 10(94%).The alkenylstannanes 19 were prepared by hydrostannation of the corresponding alkynes in moderate to high yields(42-97%),and the alkenylboronates 2 and 4 by hydroboration with catechol-borane(27-96% yield)or pinacolbor-ane(26-69% yield).
机译：钯催化六溴苯（20）与各种链烯基硼酸酯和链烯基锡烷的六重偶联反应分别提供六亚烷基苯1的产率高达73％和16％至41％。在某些情况下，五链烯基苯21被分离为主要产物还制备了一些功能性取代的在六个臂中每个含氧或硫原子的六烯基苯衍生物（产率为16％至24％）。较少受空间限制的2,3,6,7， 10,11-六溴代三亚苯基（24）以93％的产率获得了所需的六（3,3-二甲基-1-丁烯基）三亚苯基（25）。八溴萘-th（26）的首次成功的交叉偶联反应获得了八烷基-（3,3-二甲基--1-丁烯基）萘（27）的产率为21％。晶体结构分析表明，根据取代基的性质，六个臂都位于相同的一侧。如la和li中的中央苯环，使它们很好地呈杯状分子，或交替存在e和在中心平面以下，如Ih和23中所示。在27中，C-1、4、6、7处的四个臂向下，而其他臂向上，反之亦然。催化氢化时，la产生89％的六（叔丁基-乙基）苯（23）。还描述了一些有效地使用具有空间要求的取代基的炔烃的方法，从相应的甲基酮衍生的烯醇磷酸酯中消除了磷酸，得到1-乙炔基金刚烷（3b，62％收率） ），1-乙炔基-1-甲基环己烷（3c，85％）和3,3-二甲基戊炔（3e，65％）。1-（三甲基甲硅烷基）乙炔基环丙烷（7）用于制备1-乙炔基-1 -二甲基环丙烷（3d）（两步，总收率64％）。从炔丙基氯11开始，以多步顺序合成功能取代的炔烃3 fh，后者是由二甲基炔丙醇10（94％）高产率制备的。相应炔烃以中等至高产率（42-97％）进行氢化锡烷基化制备烯基锡烷19，氢化生成烯基硼酸酯2和4用儿茶酚-硼烷（产率27-96％）或频哪醇硼烷（产率26-69％）进行增产。

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