41231-78-1Relevant academic research and scientific papers
Efficient hydroarylation of terminal alkynes with sodium tetraphenylborate performed in water under mild conditions
Koci?cka,Trzeciak
, (2019/11/02)
The hydroarylation of terminal alkynes with sodium tetraphenylborate was performed in high yield within 3 h at room temperature in water, using palladium(II) complexes with imidazole ligands as catalysts. Under these conditions, differently substituted phenylacetylene substrates were converted to arylalkenes and aryl-substituted dienes. High conversion and excellent selectivity were achieved in the hydroarylation of alkynols with sodium tetraphenylborate. Only one product, arylalkene with an OH group, was formed in these reactions with the yield dependent on the kind of alkynol used. A plausible hydroarylation reaction mechanism was proposed on the basis of the palladium species identified in the reaction mixture and H/D exchange studies. The contribution of water as the hydride source was evidenced.
Selective Aerobic Oxygenation of Tertiary Allylic Alcohols with Molecular Oxygen
Zhu, Bencong,Shen, Tao,Huang, Xiaoqiang,Zhu, Yuchao,Song, Song,Jiao, Ning
supporting information, p. 11028 - 11032 (2019/07/08)
Aerobic epoxidation of tertiary allylic alcohols remains a significant challenge. Reported here is an efficient and highly chemoselective copper-catalyzed epoxidation and semipinacol rearrangement reaction of tertiary allylic alcohols with molecular oxygen. The solvent 1,4-dioxane activates dioxygen, thereby precluding the addition of a sacrificial reductant.
Synthesis, characterization, and investigations of antimicrobial activity of benzopyrans, benzofurans and spiro[4.5]decanes
Akp?nar, Deniz E.,?zgür (Nee Yakut), Mehtap,Aslan, Hakan,Alag?z, O?uzhan,?ktemer, Atilla,Dal, Hakan,H?kelek, Tuncer,Lo?o?lu, Elif
, p. 2510 - 2521 (2018/10/24)
In this study, the radical cyclization reactions of cyclic 1,3-dicarbonyl compounds (1a–c) and α,β-unsaturated alcohols (2a–d) through Mn(OAc)3 were performed. A series of biologically interesting dihydropyrans (3–5) and dihydrofurans (6–18) were synthesized as a result of these reactions. Spiro compounds (19–20) were obtained from the reactions of 1,3-dicarbonyl compounds and (E)-2,4-diphenyl-but-3-en-2-ol (2e). The unique structure of compound 19 was also confirmed by X-ray crystallography. In addition, the antibacterial activities of synthesized compounds were screened against some bacteria. Their zone diameters showed better results than some known antibiotics.
Ni-Catalyzed regio- and stereoselective addition of arylboronic acids to terminal alkynes with a directing group tether
Hari Babu, Madala,Ranjith Kumar, Gadi,Kant, Ruchir,Sridhar Reddy, Maddi
, p. 3894 - 3897 (2017/04/04)
Addition of arylboronic acids to directing group tethered acetylenes in a regio and stereoselective manner using an inexpensive catalytic system is achieved for the first time to access highly sought after allyl/homoallyl alcohol/amine units. The apparent vinylnickel intermediate was successfully trapped by the Michael electrophiles to get defined tri- and tetra-substituted olefins. An interesting selectivity switch was observed with internal alkynes.
Synthesis of dihydropyrans and dihydrofurans via radical cyclization of unsaturated alcohols and 1,3-dicarbonyl compounds
Aslan, Hakan,Akpbox Drawings Light Down And Leftnar, Deniz E.,?ktemer, Atilla,Yakut, Mehtap,Alag?z, O?uzhan
, p. 652 - 663 (2014/06/09)
The oxidative cyclization reactions of 1,3-dicarbonyl compounds 1a-1c and α,β-unsaturated alcohols 2a-2f with Mn(OAc)3 were performed, leading to dihydrofurans. Treatment of 1a and 1b with 2-methylbut-3-en-2-ol (2a) gave dihydrofurans 3aa and 3ba, and dihydropyrans 4aa and 4ba, as unexpected products. While the reaction of 2-methylbut-3-yn-2-ol (2b) with acetylacetone (1b) yielded a bifuran, ethyl acetoacetate (1a) led to a mixture of furan, bifuran, and salicylate derivatives. Besides, surprisingly, styryl-substituted dihydrofurans were obtained from the reactions of 1,3-dicarbonyl compounds and (3E)-2,4-diphenylbut-3-en-2-ol. The reaction mechanisms were proposed for the formation of the different products, considering intermediates in these reaction mixtures. Copyright
Catalytic Enantioselective Addition of Aryl Grignard Reagents to Ketones
Fernández-Mateos, Emilio,Maciá, Beatriz,Yus, Miguel
, p. 6519 - 6526 (2016/02/18)
We report a catalytic system for the challenging enantioselective addition of aryl Grignard reagents to ketones. Using a simple, one-pot procedure under mild conditions, a wide range of aromatic ketones are converted into diaryl alcohols in good yields and with good enantioselectivities. The catalytic enantioselective addition of aryl Grignard reagents to ketones is now possible. Using a readily available Ar-BINMOL ligand and titanium(IV) isopropoxide in a simple, one-pot procedure under mild conditions, a wide range of aromatic ketones are converted into diaryl alcohols in good yields and with good enantioselectivities.
Cooperative titanocene and phosphine catalysis: Accelerated C-X activation for the generation of reactive organometallics
Fleury, Lauren M.,Kosal, Andrew D.,Masters, James T.,Ashfeld, Brandon L.
, p. 253 - 269 (2013/03/14)
The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C-X bonds at temperatures as low as -40 °C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.
Lithium choreography: Intramolecular arylations of carbamate-stabilised carbanions and their mechanisms probed by in situ IR spectroscopy and DFT calculations
Fournier, Anne M.,Nichols, Christopher J.,Vincent, Mark A.,Hillier, Ian H.,Clayden, Jonathan
, p. 16478 - 16490 (2013/02/23)
Deprotonation of O-allyl, O-propargyl or O-benzyl carbamates in the presence of a lithium counterion leads to carbamate-stabilised organolithium compounds that may be quenched with electrophiles. We now report that when the allylic, propargylic or benzylic carbamate bears an N-aryl substituent, an aryl migration takes place, leading to stereochemical inversion and C-arylation of the carbamate α to oxygen. The aryl migration is an intramolecular S NAr reaction, despite the lack of anion-stabilising aryl substituents. Our in situ IR studies reveal a number of intermediates along the rearrangement pathway, including a "pre-lithiation complex," the deprotonated carbamate, the rearranged anion, and the final arylated carbamate. No evidence was obtained for a dearomatised intermediate during the aryl migration. DFT calculations predict that during the reaction the solvated Li cation moves from the carbanion centre, thus freeing its lone pair for nucleophilic attack on the remote phenyl ring. This charge separation leads to several alternative conformations. The one having Li+ bound to the carbamate oxygen gives rise to the lowest-energy transition structure, and also leads to inversion of the configuration. In agreement with the IR studies, the DFT calculations fail to locate a dearomatised intermediate. Dancing to lithium's tune: In situ IR spectroscopy and DFT calculations allow the detailed pathways of aryl migrations taking place in lithiated carbamates to be characterised (see scheme).
New and efficient synthesis of solid-supported organotin reagents and their use in organic synthesis
Hernán, Alejandro G.,Horton, Peter N.,Hursthouse, Michael B.,Kilburn, Jeremy D.
, p. 1466 - 1475 (2007/10/03)
Novel resin-bound organotin reagents have been prepared, including for the first time resin-bound dimethyl tin reagents. Mild methodology has also been developed for the very efficient synthesis of resin-bound distannanes. The resin-bound tin chloride rea
Effect of InCl3 on the addition of Grignard reagents to α,β-unsaturated carbonyl compounds
Kelly, Brian G.,Gilheany, Declan G.
, p. 887 - 890 (2007/10/03)
Control of 1,2- versus 1,4-addition of organometallic reagents to enones remains a long-standing problem. There is still no satisfactory 1,2-directing agent comparable to the 1,4-directing effect of copper salts. We report that the presence of just 5 mol% indium(III) chloride can significantly alter the amount of 1,2-product formed in these reactions.
