A Highly Efficient Access to Spiroketals, Mono-unsaturated Spiroketals, and Furans: Hg(II)-Catalyzed Cyclization of Alkyne Diols and Triols
摘要:
Hg(II) salts are identified as highly efficient catalysts for the versatile construction of spiroketals from alkyne diols in aqueous conditions. Monounsaturated spiroketals and furans were accessed with equal ease when propargylic triols (or propargylic diols) were subjected to similar conditions. Even the semiprotected alkyne diols gave the corresponding spiroketals with the same ease in a cascade manner. The reactions are Instant and high yielding at ambient temperatures. Regioselectivity issues are well addressed.
double hydroalkoxylation of internal alkynes could be achieved using a Grubbs-type ruthenium carbene complex or its modified species to deliver a series of bridged- and spiroacetal derivatives in moderate to good yields. This study represents a new example of nonmetathetic reactions catalyzed by Grubbs-type ruthenium carbene complexes.
Highly efficient Rh(i) and Ir(i) single and dual metal catalysed dihydroalkoxylation reactions of alkyne diols
作者:Joanne Hui Hui Ho、Richard Hodgson、Jörg Wagler、Barbara Ann Messerle
DOI:10.1039/b926773e
日期:——
A highly efficient rhodium(I) and iridium(I) catalysed dihydroalkoxylation reaction of alkyne diols is employed here for the synthesis of spiroketals and a fused bicyclicketal. The two metal catalysts show differential selectivity and efficiency for either the cyclisation of the 5-exo or 6-endo-membered rings. For the first time, a dual metal (Rh and Ir) catalyst system is effectively utilised for
Gold(III) NHC Complexes for Catalyzing Dihydroalkoxylation and Hydroamination Reactions
作者:Ashwin G. Nair、Roy T. McBurney、Mark R. D. Gatus、Samantha C. Binding、Barbara A. Messerle
DOI:10.1021/acs.inorgchem.7b02161
日期:2017.10.2
Furthermore, [LAu(III)Cl3] catalyzed intra- and intermolecular hydroamination reactions, achieving good to excellent conversions. [LAu(III)Cl3] is a more efficient catalyst than a gold(I) analogue, [LAu(I)Cl]. The dependence of the quantity of weakly coordinating anion [BArF4]− ((3,5-trifluoromethyl)phenyl borate) present on catalysis efficiency was probed for the dihydroalkoxylation reaction. X-ray diffraction
N-杂环卡宾基半不稳定配体与两个侧重吡唑臂(1,3-双((1 H-吡唑-3-基)甲基)-2,3-二氢-1 H-咪唑的金(III)络合物,LH)被合成。络合物[ L Au(III)Cl 3 ]是在室温下甚至在0℃下催化该反应的促进二氢烷氧基化的极好的催化剂。[ L Au(III)Cl 3 ]是迄今为止报道的炔二醇螺环化最有效的催化剂之一。此外,[ L Au(III)Cl 3 ]催化了分子内和分子间加氢胺化反应,实现了良好的转化率。[ L Au(III)Cl3 ]是一种比金(I)类似物[ L Au(I)Cl]更有效的催化剂。对于二氢烷氧基化反应,探查了存在的弱配位阴离子[BAr F 4 ] -((3,5-三氟甲基)苯基硼酸酯)的量对催化效率的依赖性。单晶的X射线衍射分析表明,金配合物[ L Au(III)Cl 3 ]和[ L Au(I)Cl]的固态结构分别显示了预期的正方形平面和线性配位几何形状。
Silver-zeolite catalysed solvent free synthesis of (spiro)ketals
作者:Sophie Borghèse、Pauline Drouhin、Valérie Bénéteau、Benoit Louis、Patrick Pale
DOI:10.1039/c3gc40422f
日期:——
were able to catalyse, without solvents and at low silver loading, the formation of (spiro)ketals from alkyn(edi)ols. Such Ag-zeolite catalysts could be recycled without any activity loss. This study constitutes the first (spiro)ketalization mediated by silver heterogeneous catalysts, but also a truly ‘green’ (spiro)ketalization.
The synthesis of the bisbenzannelated spiroketal core of natural bioactive rubromycins via a gold-catalyzed double intramolecular hydroalkoxylation was described. A comparative study on the formation of aliphatic and of aromatic spiroketals was also conducted.