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首页> 外文期刊>Chemistry: A European journal >Highly regioselective hydroformylation with hemispherical chelators
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Highly regioselective hydroformylation with hemispherical chelators

机译：半球形螯合剂的高度区域选择性加氢甲酰化

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摘要

The hemispherical diphosphites (R,R)- or (S,S)-5,11,17,23-tetra-tert-butyl-25,27-di(OR)-26,28-bis(1,1'-binaphthyl-2,2'-dioxyphosphanyloxy)- calix[4]arene (R = OPr, OCH2Ph OCH2-naphtyl, O-fluorenyl; R=H, R'=OPr) (L-R), all with C-2 symmetry, have been synthesised starting from the appropriate di-O-alkylated calix[4]arene precursor. In the presence of [Rh(acac)(CO)(2)], these ligands straightforwardly provide chelate complexes ill which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C-2 axis and the two apically situated R groups. Hydroformylation of octene with the L-Pr/Rh system turned out to be highly regioselective, the linear-to-branched (1:b) aldehyde ratio reaching 58:1. The 1:b ratio significantly increased when the propyl groups were replaced by -CH2Ph (1:b=80) or -CH(2)naphthyl (1:b = 100) groups, that is, with substituents able to sterically interact with the apical metal sites, but without inducing all opening of the cleft nesting the catalytic centre. The trend to preferentially form the aldehyde the shape of which fits with the shape of the catalytic pocket was further confirmed in the hydroformylation of styrene, for which, in contrast to catalysis with conventional diphosphanes, the linear aldehyde was the major product (up to ca. 75% linear aldehyde). In the hydroformylation of trans-2-octene with the L-benzyl/ Rh system, combined isomerisation/hydroformylation led to it remarkably high I:b aldehyde ratios of 25, thus showing that isomerisation is more effective than hydroformylation. Unusually large amounts of linear products were also observed with all the above diphosphites in the tandem hydroformylation/amination of styrene (1:b of ca. 3:1) as well as in the hydroformylation of allyl benzyl ether (1:b ratio up to 20).
机译：半球形二亚磷酸酯（R，R）-或（S，S）-5,11,17,23-四叔丁基-25,27-di（OR）-26,28-双（1,1'-双萘基2,2'-二氧基膦酰氧基）-杯[4]亚芳基（R = OPr，OCH2Ph OCH2-萘基，O-芴基; R = H，R'= OPr）（LR），均具有C-2对称性，具有从合适的二-O-烷基化杯[4]芳烃前体开始合成α-己内酰胺。在[Rh（acac）（CO）（2）]的存在下，这些配体直接提供螯合物，直到金属中心位于由两个与C-2轴相关的萘平面和两个位于顶部的萘基定义的分子口袋中R组。事实证明，使用L-Pr / Rh系统进行的辛烯加氢甲酰化具有很高的区域选择性，线性与分支的醛比例（1：b）达到58：1。当丙基被-CH2Ph（1：b = 80）或-CH（2）萘基（1：b = 100）基团取代时（即，能够与该基团空间相互作用的取代基），1：b比例显着增加。顶端金属位点，但不会导致裂隙的所有开口都嵌套在催化中心。在苯乙烯的加氢甲酰化反应中，进一步证实了优先形成其形状与催化口袋形状相符的醛的趋势，与常规二膦烷的催化作用相比，线性醛是主要的产物（直至75％的线性醛）在反式-2-辛烯与L-苄基/ Rh系统的加氢甲酰化中，异构化/加氢甲酰化的结合导致I / b醛比率高达25，因此异构化比加氢甲酰化更有效。在苯乙烯的串联加氢甲酰化/胺化反应（约3：1的1：b）以及烯丙基苄基醚的加氢甲酰化反应中（最高1：b的比例），在所有上述二亚磷酸酯中也观察到异常大量的线性产物20）。

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