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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >[PhSiO1.5](8,10,12) as nanoreactors for non-enzymatic introduction of ortho, meta or para-hydroxyl groups to aromatic molecules
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[PhSiO1.5](8,10,12) as nanoreactors for non-enzymatic introduction of ortho, meta or para-hydroxyl groups to aromatic molecules

机译：[PHSIO1.5]（8,10,12）作为纳米反应器，用于非酶促引入邻邻，Meta或Para-羟基至芳族分子

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Traditional electrophilic bromination follows long established "rules": electron-withdrawing substituents cause bromination selective for meta positions, whereas electron-donating substituents favor ortho and para bromination. In contrast, in the [PhSiO1.5](8,10,12) silsesquioxanes, the cages act as bulky, electron withdrawing groups equivalent to CF3; yet bromination under mild conditions, without a catalyst, greatly favors ortho substitution. Surprisingly, ICl iodination without a catalyst favors (>90%) para substitution [p-IC6H4SiO1.5](8,10,12). Finally, nitration and Friedel-Crafts acylation and sulfonylation are highly meta selective, >80%. In principle, the two halogenation formats coupled with the traditional electrophilic reactions provide selective functionalization at each position on the aromatic ring. Furthermore, halogenation serves as a starting point for the synthesis of two structural isomers of practical utility, i.e. in drug prospecting. The o-bromo and p-iodo compounds are easily modified by catalytic cross-coupling to append diverse functional groups. Thereafter, F-/H2O2 treatment cleaves the Si-C bonds replacing Si with OH. This represents a rare opportunity to introduce hydroxyl groups to aromatic rings, a process not easily accomplished using traditional organic synthesis methods. The as-produced phenol provides additional opportunities for modification. Each cage can be considered a nanoreactor generating 8-12 product molecules. Examples given include syntheses of 4,2'-R, OH-stilbenes and 4,4'-R, OH-stilbenes (R = Me, CN). Unoptimized cleavage of the Br/I derivatives yields 55-85% phenol. Unoptimized cleavage of the stilbene derivatives yields 35-40% (3-5 equivalents of phenol) in the preliminary studies presented here. In contrast, meta R-phenol yields are 80% (7-10 mol per cage).
机译：传统的亲电溴化均匀遵循长期的“规则”：吸电子取代基因溴化溴定位，而电子给予取代基赞成邻摩尔和对溴化溴。相比之下，在[phsio1.5]（8,10,12）倍半硅氧烷中，笼子充当笨重的电子抽出基团，其等于CF3;然而，在温和的条件下溴化，没有催化剂，极大地归因于替代。令人惊讶的是，没有催化剂的ICL碘化（> 90％）对替代[P-IC6H4SIO1.5]（8,10,12）。最后，硝化和Friedel-Crafts酰化和磺酰化是高度的Meta选择性，> 80％。原则上，与传统的亲电子反应相结合的两个卤化形式为芳环上的每个位置提供选择性官能化。此外，卤化物用作合成实用效用的两个结构异构体的起点，即在药物勘探中。通过催化交联伴催化交叉偶联容易改性O-Bromo和P-Iodo化合物以附录不同的官能团。此后，F- / H 2 O 2处理切割替代Si的Si-C键合哦。这代表了将羟基引入芳环的罕见机会，该方法不容易使用传统的有机合成方法完成。制作的苯酚提供修改的额外机会。每个笼子可以被认为是产生8-12个产品分子的纳米反应器。给出的实例包括4,2'-R，OH-斯蒂芬和4,4'-R，OH-斯蒂芬（R = ME，CN）的合成。非优化的Br / I衍生物的切割产生55-85％的苯酚。在此处提出的初步研究中，斯蒂尔贝衍生物的未优化裂解产生35-40％（3-5当量的苯酚）。相反，Meta R-苯酚产率为80％（每个笼子7-10摩尔）。

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