818-72-4Relevant articles and documents
Rhodium-Catalyzed Parallel Kinetic Resolution of Racemic Internal Allenes Towards Enantiopure Allylic 1,3-Diketones
Hilpert, Lukas J.,Breit, Bernhard
supporting information, p. 9939 - 9943 (2019/06/24)
A rare case of a parallel kinetic resolution of racemic 1,3-disubstituted allenes by means of a rhodium-catalyzed addition to 1,3-diketones furnishing enantiopure allylic 1,3-diketones is described. Mechanistic experiments demonstrate that the different allene enantiomers react in parallel to either the diastereomeric E- or Z-allylic 1,3-diketones with the same absolute configuration of the newly formed stereogenic center. A broad substrate scope demonstrates the synthetic utility of this new method.
1,1-Diphosphines and divinylphosphines via base catalyzed hydrophosphination
Coles,Mahon,Webster
, p. 10443 - 10446 (2018/09/21)
A catalytic hydrophosphination route to 1,1-diphosphines is yet to be reported: these narrow bite angle pro-ligands have been used to great effect as ligands in homogeneous catalysis. We herein demonstrate that terminal alkynes readily undergo double hydrophosphination with HPPh2 and catalytic potassium hexamethyldisilazane (KHMDS) to generate 1,1-diphosphines. A change to H2PPh leads to the formation of P,P-divinyl phosphines.
Diversification of ortho-Fused Cycloocta-2,5-dien-1-one Cores and Eight- to Six-Ring Conversion by σ Bond C?C Cleavage
Eccleshare, Lee,Lozada-Rodríguez, Leticia,Cooper, Phillippa,Burroughs, Laurence,Ritchie, John,Lewis, William,Woodward, Simon
supporting information, p. 12542 - 12547 (2016/08/24)
Sequential treatment of 2-C6H4Br(CHO) with LiC≡CR1(R1=SiMe3, tBu), nBuLi, CuBr?SMe2and HC≡CCHClR2[R2=Ph, 4-CF3Ph, 3-CNPh, 4-(MeO2C)Ph] at ?50 °C leads to formation of an intermediate carbanion (Z)-1,2-C6H4{CA(=O)C≡CBR1}{CH=CH(CH?)R2} (4). Low temperatures (?50 °C) favour attack at CBleading to kinetic formation of 6,8-bicycles containing non-classical C-carbanion enolates (5). Higher temperatures (?10 °C to ambient) and electron-deficient R2favour retro σ-bond C?C cleavage regenerating 4, which subsequently closes on CAproviding 6,6-bicyclic alkoxides (6). Computational modelling (CBS-QB3) indicated that both pathways are viable and of similar energies. Reaction of 6 with H+gave 1,2-dihydronaphthalen-1-ols, or under dehydrating conditions, 2-aryl-1-alkynylnaphthlenes. Enolates 5 react in situ with: H2O, D2O, I2, allylbromide, S2Me2, CO2and lead to the expected C-E derivatives (E=H, D, I, allyl, SMe, CO2H) in 49–64 % yield directly from intermediate 5. The parents (E=H; R1=SiMe3, tBu; R2=Ph) are versatile starting materials for NaBH4and Grignard C=O additions, desilylation (when R1=SiMe) and oxime formation. The latter allows formation of 6,9-bicyclics via Beckmann rearrangement. The 6,8-ring iodides are suitable Suzuki precursors for Pd-catalysed C?C coupling (81–87 %), whereas the carboxylic acids readily form amides under T3P conditions (71–95 %).
Styrene as 4π-Component in Zn(II)-Catalyzed Intermolecular Diels-Alder/Ene Tandem Reaction
Zheng, Min,Wu, Feng,Chen, Kai,Zhu, Shifa
supporting information, p. 3554 - 3557 (2016/08/16)
A mild Zn-catalyzed intermolecular Diels-Alder/ene tandem reaction with styrene as a 4π-component is reported. A variety of dihydronaphthalene products could be prepared in moderate to good yields. Moreover, a combination of DFT calculations and experiments was performed to further understand the mechanism of this unique tandem reaction.
Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt as efficient mild polymeric solid acid catalyst
Tanemura, Kiyoshi,Suzuki, Tsuneo
supporting information, p. 6740 - 6743 (2013/11/19)
Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt was easily prepared by the reaction of aniline with 1.25 equiv of terephthalaldehyde in the presence of 1.0 equiv of p-toluenesulfonic acid at 75 C for 24 h in EtOH. ATRT efficiently catalyzed the tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl (THP), triethylsilyl (TES), and tert-butyldimethylsilyl (TBDMS) ethers. Deprotection of dodecyl THP ether and dodecyl TBDMS ether catalyzed by ATRT proceeded faster than those by pyridinium p-toluenesulfonate (PPTS). ATRT was reused without significant loss of activities.
Facile access to 2,5-disubstituted-4-chloromethyl-3-iodofuran derivatives via ICl-mediated cyclization of 1-alkyl-2-alkynylallylic alcohols
Thongsornkleeb, Charnsak,Rabten, Wangchuk,Ruchirawat, Somsak,Bunrit, Anon,Tummatorn, Jumreang
, p. 6615 - 6619,5 (2012/12/11)
Substituted furans are conveniently synthesized from acyclic secondary 1-alkyl-2-alkynylallylic alcohol precursors via an ICl-promoted cyclization reaction. The furans generated by this method incorporate both iodine and chlorine atoms which may be useful for further elaborations via many known methods. The methodology is suitable for generating a wide array of furan products which can serve as useful building blocks for the synthesis of various biologically active molecules.
Facile access to 2,5-disubstituted-4-chloromethyl-3-iodofuran derivatives via ICl-mediated cyclization of 1-alkyl-2-alkynylallylic alcohols
Thongsornkleeb, Charnsak,Rabten, Wangchuk,Bunrit, Anon,Tummatorn, Jumreang,Ruchirawat, Somsak
, p. 6615 - 6619 (2013/01/15)
Substituted furans are conveniently synthesized from acyclic secondary 1-alkyl-2-alkynylallylic alcohol precursors via an ICl-promoted cyclization reaction. The furans generated by this method incorporate both iodine and chlorine atoms which may be useful for further elaborations via many known methods. The methodology is suitable for generating a wide array of furan products which can serve as useful building blocks for the synthesis of various biologically active molecules.
Enantioselective copper-catalysed propargylic substitution: Synthetic scope study and application in formal total syntheses of (+)-anisomycin and (-)-cytoxazone
Detz, Remko J.,Abiri, Zohar,Le Griel, Remi,Hiemstra, Henk,Van Maarseveen, Jan H.
experimental part, p. 5921 - 5930 (2011/06/26)
A copper catalyst with a chiral pyridine-2,6-bisoxazoline (pybox) ligand was used to convert a variety of propargylic esters with different side chains (R=Ar, Bn, alkyl) into their amine counterparts in very high yields and with good enantioselectivities (up to 90% enantiomeric excess (ee)). Different amine nucleophiles were applied in the reactions and the highest enantioselectivities were obtained for aniline and its analogues. Interestingly, some carbon nucleophiles could also be used and with indoles excellent ee values were obtained (up to 98% ee). The versatility of the propargylic amines obtained was demonstrated by their further elaboration to formal total syntheses of the antibiotic (+)-anisomycin and the cytokine modulator (-)-cytoxazone. Copyright
Three-component reaction for the C2-functionalization of 1-substituted imidazoles with acetylenic ketones and isocyanates
Shen, Yang,Cai, Shuying,He, Chi,Lin, Xufeng,Lu, Ping,Wang, Yanguang
supporting information; experimental part, p. 8338 - 8342 (2011/11/12)
An efficient method for the direct C2-amidation of 1-substituted imidazoles with acetylenic ketones and isocyanates is reported. This three-component procedure has the advantages of catalyst-free, operational simplicity, mild reaction conditions, and good to excellent yields.
Gold-catalyzed ethynylation of arenes
De Haro, Teresa,Nevado, Cristina
experimental part, p. 1512 - 1513 (2010/04/04)
(Figure Presented) A novel gold-catalyzed ethynylation of aromatic rings with electron-deficient alkynes via gold catalyzed C-H activation of both C sp-H and Csp2-H bonds has been developed. This transformation provides aromatic propiolates difficult to prepare by other methods, highlighting the synthetic potential of gold chemistry.
