66022-00-2Relevant articles and documents
Ni-Catalyzed Cycloisomerization between 3-Phenoxy Acrylic Acid Derivatives and Alkynes via Intramolecular Cleavage and Formation of the C-O Bond to Give 2,3-Disubstituted Benzofurans
Ohno, Shohei,Qiu, Jiawei,Miyazaki, Ray,Aoyama, Hiroshi,Murai, Kenichi,Hasegawa, Jun-Ya,Arisawa, Mitsuhiro
supporting information, p. 8400 - 8403 (2019/10/14)
Reactions based on transition-metal-catalyzed C-O bond cleavage have attracted much attention as a new synthetic method. Until now, several intermolecular reactions via C-O bond cleavage of aryl ethers, alkenyl ethers, esters, and others have been reported. Here we report an unprecedented C-O bond cleavage of 3-phenoxy acrylic acid derivatives, followed by intramolecular C-O bond formation with alkynes. This reaction gave 2,3-disubstituted benzofurans having useful functional groups-silyl substituents and acrylic acid derivatives- A t the 2- A nd 3-positions, respectively. This report also described theoretical (DFT) insights into the mechanism.
An Iron-Catalyzed Bond-Making/Bond-Breaking Cascade Merges Cycloisomerization and Cross-Coupling Chemistry
Echeverria, Pierre -Georges,Fürstner, Alois
, p. 11188 - 11192 (2016/10/13)
Treatment of readily available enynes with alkyl-Grignard reagents in the presence of catalytic amounts of Fe(acac)3engenders a remarkably facile and efficient reaction cascade that results in the net formation of two new C?C bonds while a C?Z bond in the substrate backbone is broken. Not only does this new manifold lend itself to the extrusion of heteroelements (Z=O, NR), but it can even be used for the cleavage of activated C?C bonds. The reaction likely proceeds via metallacyclic intermediates, the iron center of which gains ate character before reductive elimination occurs. The overall transformation represents a previously unknown merger of cycloisomerization and cross-coupling chemistry. It provides ready access to highly functionalized 1,3-dienes comprising a stereodefined tetrasubstituted alkene unit, which are difficult to make by conventional means.
A new method for the preparation of non-terminal alkynes: Application to the total syntheses of tulearin A and C
Lehr, Konrad,Schulthoff, Saskia,Ueda, Yoshihiro,Mariz, Ronaldo,Leseurre, Lucie,Gabor, Barbara,Fürstner, Alois
supporting information, p. 219 - 227 (2015/02/19)
Lactones are known to react with the reagent generated in situ from CCl4 and PPh3 in a Wittig-type fashion to give gem-dichloro-olefin derivatives. Such compounds are now shown to undergo reductive alkylation on treatment with organolithium reagents RLi to furnish acetylene derivatives bearing the substituent R at their termini (R=Me, n-, sec-, tert-alkyl, silyl); the reaction can be catalyzed with either Cu(acac)2 or Fe(acac)3/1,2-diaminobenzene. Two alkynol derivatives prepared in this way from readily accessible lactone precursors served as the key building blocks for the total syntheses of the cytotoxic marine macrolides tulearin A (1) and C (2). The assembly of these fragile targets hinged upon ring closing alkyne metathesis (RCAM) followed by a formal trans-reduction of the resulting cycloalkynes via trans-hydrosilylation/protodesilylation.
Switching reaction pathways of benzo[b]thiophen-3-yllithium and benzo[b]furan-3-yllithium based on high-resolution residence-time and temperature control in a flow microreactor
Asai, Tatsuro,Takata, Atsushi,Ushiogi, Yousuke,Iinuma, Yoshiharu,Nagaki, Aiichiro,Yoshida, Jun-Ichi
supporting information; experimental part, p. 393 - 395 (2011/05/03)
Reaction-pathway control of benzo[b]thiophen-3-yllithium and benzo[b]furan-3-yllithium was accomplished in flow microreactor systems. We could switch between the reaction with an electrophile before ring-opening and that after ring-opening at will by choosing an appropriate residence-time and temperature.
An intra/intermolecular suzuki sequence to benzopyridyloxepines containing geometrically pure exocyclic tetrasubstituted alkenes
Carson, Matthew W.,Giese, Matthew W.,Coghlan, Michael J.
supporting information; experimental part, p. 2701 - 2704 (2009/05/26)
(Chemical Equation Presented) A route to enable the preparation of 5-benzylidenyl-benzopyridyloxepine analogues was developed to continue our research in the field of nuclear hormone receptor modulators. The key steps are1) a syn-stereoselective diboratio
Rhodium-catalysed cyclic carbonylation of 2-alkynylphenols: Synthesis of benzofuranones and coumarins
Yoneda, Eiji,Sugioka, Takashi,Hirao, Kojiro,Zhahg, Shi-Wei,Takahashi, Shigetoshi
, p. 477 - 483 (2007/10/03)
Rhodium-catalysed carbonylation of 2-alkynylphenols 1 under water-gas shift reaction conditions gives benzofuranone derivatives 2 and coumarin derivatives 3 in high yield (up to 96%, 2:3 = 65:35), in which the hydroxy group adjacent to the carbon-carbon triple bond participitates in the cyclic carbonylation.
A New Preparation of Benzofurans Utilizing Trimethylsilyldiazomethane
Ito, Yasuko,Aoyama, Toyohiko,Shioiri, Takayuki
, p. 1163 - 1164 (2007/10/03)
o-Triisopropylsiloxyaryl ketones and aldehydes smoothly reacted with the lithium salt of trimethylsilyldiazomethane to give o-triisopropylsiloxyphenylacetylenes which were easily converted to benzofurans by treatment with tetra-n-butylammonium fluoride. 3-Benzofuranmethanols were also obtained when the reaction was conducted in the presence of carbonyl compounds.
