Synthesis of 6-oxacyclopropa[a]indene derivatives starting from Baylis–Hillman adducts via Pd-mediated C(sp3)–H activation
摘要:
We prepared novel 1-phenyl-1,6a-dihydro-6-oxacyclopropa[a]indene-1a-carboxylic acid derivatives starting from the Baylis-Hillman adducts via the palladium-mediated domino carbopalladation involving activation of C(sp(3))-H bond, (c) 2008 Elsevier Ltd. All rights reserved.
Allylicarylation of cinnamyloxyphenylboronic acid pinacol esters 3, which have arylboronicacid moiety and allylicether moiety, using a hydrazone 1d–Pd(OAc)2 system proceeded and gave the corresponding 1,3-diarylpropene derivatives 4 with a phenolic hydroxyl group via a selective coupling reaction of the π-allyl intermediate to the boron-substituted position of the leaving group.
Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel‐catalyzed domino cyclization–condensation process. This reaction, which does not require the preparation of any other organometallic reagent, proceeds only by exo‐dig cyclization. This convenient and mild method constitutes a one‐pot synthesis of substituted dihydrobenzofurans
Reaction of Ni(0) in the presence of iodoarylethers 1 leads, after syn intramolecular carbonickelation of the triple bond, to nucleophilic vinylnickels which can be trapped, in a tandem process, by various electrophiles introduced at the onset of the reaction.
The intramolecularcarbolithiation of a series of propargylic ethers has been performed to evaluate the influence of the terminal substituent on the efficiency and the stereochemical outcome of the cyclization. Our results show that only 5-exo-dig cyclizations are observed, and dihydrobenzofurans are obtained exclusively. Depending on the nature of the terminal substituent, two cases can be considered
已经进行了一系列炔丙醚的分子内碳锂化,以评估末端取代基对环化效率和立体化学结果的影响。我们的结果表明,仅观察到 5-exo-dig 环化,并且仅获得了二氢苯并呋喃。根据末端取代基的性质,可以考虑两种情况。如果炔烃碳原子携带的末端取代基本身是碳原子,则只要末端炔丙基位置带有配位元素并且至少是二取代的,就可以发生环化。当环化发生时,它遵循反碳石化途径,从而导致环外双键的 E 异构体。仅在一种情况下(Ph)是回收的所得烯烃的E和Z异构体的混合物。如果调节环化条件,炔烃直接被 S 或 Si 取代,也可以发生环化。在三甲基甲硅烷基取代基的情况下,观察到顺式碳锂化。如果双键被恢复,在大多数情况下,在环外位置,产物可以直接芳构化为 SPh 取代的底物 24。此外,在后两种情况下,当进行乙烯基锂中间体的烷基化时,双键的异构化似乎是瞬间的。
Monohydride‐Dichloro Rhodium(III) Complexes with Chiral Diphosphine Ligands as Catalysts for Asymmetric Hydrogenation of Olefinic Substrates
full details of the synthesis and characterization of monohydride‐dichloro rhodium(III) complexes bearing chiral diphosphine ligands, such as (S )‐BINAP, (S )‐DM‐SEGPHOS, and (S )‐DTBM‐SEGPHOS, producing cationic triply chloride bridged dinuclear rhodium(III) complexes (1 a : (S )‐BINAP; 1 b : (S )‐DM‐SEGPHOS) and a neutral mononuclear monohydride‐dichloro rhodium(III) complex (1 c : (S )‐DTBM‐SEGPHOS)