72656-49-6Relevant academic research and scientific papers
SO2F2-Mediated Oxidative Dehydrogenation and Dehydration of Alcohols to Alkynes
Zha, Gao-Feng,Fang, Wan-Yin,Li, You-Gui,Leng, Jing,Chen, Xing,Qin, Hua-Li
supporting information, p. 17666 - 17673 (2019/01/04)
Direct synthesis of alkynes from inexpensive, abundant alcohols was achieved in high yields (greater than 40 examples, up to 95% yield) through a SO2F2-promoted dehydration and dehydrogenation process. This straightforward transformation of sp3-sp3 (C-C) bonds to sp-sp (C=C) bonds requires only inexpensive and readily available reagents (no transition metals) under mild conditions. The crude alkynes are sufficiently free of impurities to permit direct use in further transformations, as illustrated by regioselective Huisgen alkyne-azide cycloaddition reactions with PhN3 to give 1,4-substituted 1,2,3-traiazoles (16 examples, up to 92% yield) and Sonogashira couplings (10 examples, up to 77% yield).
Heterogeneous versus homogeneous copper(II) catalysis in enantioselective conjugate-addition reactions of boron in water
Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
supporting information, p. 179 - 188 (2014/01/06)
We have developed CuII-catalyzed enantioselective conjugate-addition reactions of boron to α,β-unsaturated carbonyl compounds and α,β,γ,δ-unsaturated carbonyl compounds in water. In contrast to the previously reported CuI catalysis that required organic solvents, chiral CuII catalysis was found to proceed efficiently in water. Three catalyst systems have been exploited: cat. 1: Cu(OH)2 with chiral ligand L1; cat. 2: Cu(OH)2 and acetic acid with ligand L1; and cat. 3: Cu(OAc)2 with ligand L1. Whereas cat. 1 is a heterogeneous system, cat. 2 and cat. 3 are homogeneous systems. We tested 27 α,β-unsaturated carbonyl compounds and an α,β-unsaturated nitrile compound, including acyclic and cyclic α,β-unsaturated ketones, acyclic and cyclic β,β- disubstituted enones, acyclic and cyclic α,β-unsaturated esters (including their β,β-disubstituted forms), and acyclic α,β-unsaturated amides (including their β,β-disubstituted forms). We found that cat. 2 and cat. 3 showed high yields and enantioselectivities for almost all substrates. Notably, no catalysts that can tolerate all of these substrates with high yields and high enantioselectivities have been reported for the conjugate addition of boron. Heterogeneous cat. 1 also gave high yields and enantioselectivities with some substrates and also gave the highest TOF (43 200 h-1) for an asymmetric conjugate-addition reaction of boron. In addition, the catalyst systems were also applicable to the conjugate addition of boron to α,β,γ, δ-unsaturated carbonyl compounds, although such reactions have previously been very limited in the literature, even in organic solvents. 1,4-Addition products were obtained in high yields and enantioselectivities in the reactions of acyclic α,β,γ,δ-unsaturated carbonyl compounds with diboron 2 by using cat. 1, cat. 2, or cat. 3. On the other hand, in the reactions of cyclic α,β,γ,δ-unsaturated carbonyl compounds with compound 2, whereas 1,4-addition products were exclusively obtained by using cat. 2 or cat. 3, 1,6-addition products were exclusively produced by using cat. 1. Similar unique reactivities and selectivities were also shown in the reactions of cyclic trienones. Finally, the reaction mechanisms of these unique conjugate-addition reactions in water were investigated and we propose stereochemical models that are supported by X-ray crystallography and MS (ESI) analysis. Although the role of water has not been completely revealed, water is expected to be effective in the activation of a borylcopper(II) intermediate and a protonation event subsequent to the nucleophilic addition step, thereby leading to overwhelmingly high catalytic turnover. Copyright
N-heterocyclic carbene mediated Reformatsky reaction of aldehydes with a-trimethylsilylcarbonyl compounds
Zou, Xiao-Lei,Du, Guang-Fen,Sun, Wan-Fu,He, Lin,Ma, Xiao-Wei,Gu, Cheng-Zhi,Dai, Bin
, p. 607 - 612 (2013/07/27)
N-Heterocyclic carbenes have been employed as highly efficient organocatalysts to mediate silyl-Reformatsky type reaction. In the presence of only 0.5 mol % nucleophilic carbene 1, various aldehydes coupled with α-trimethylsilylethylacetate very smoothly in DMF at room temperature to provide the corresponding β-hydroxyesters in moderate to high yields. α-Trimethylsilylketone and α-trimethylsilylamide can also undergo the addition reaction to give β-hydroxyketone and b-hydroxyamide in moderate yields.
Chiral copper(II)-catalyzed enantioselective boron conjugate additions to α,β-unsaturated carbonyl compounds in water
Kobayashi, Shu,Xu, Pengyu,Endo, Toshimitsu,Ueno, Masaharu,Kitanosono, Taku
, p. 12763 - 12766 (2013/02/22)
Copper pins on the boron: The enantioselective 1,4-addition of diboron to α,β-unsaturated compounds proceeds smoothly in the presence of catalytic amounts of Cu(OH)2 and chiral 2,2′-bipyridine ligand in water. A wide substrate scope of α,β-unsaturated carbonyl compounds, including acyclic, cyclic, and β,β-disubstituted enones, α,β-unsaturated esters, amides, and a nitrile, has been shown. Copyright
Optically active thiophenes via an organocatalytic one-pot methodology
Ransborg, Lars Krogager,Albrecht, Lukasz,Weise, Christian F.,Bak, Jesper R.,Jorgensen, Karl Anker
supporting information; experimental part, p. 724 - 727 (2012/04/11)
A general methodology for the synthesis of trisubstituted, optically active thiophenes by an organocatalytic one-pot reaction cascade is presented. The target products are synthesized in good yields (up to 92%) and with excellent enantioselectivities (up to 98% ee). Importantly, based on practical and easily available starting materials, the presented methodology can be conducted under mild reaction conditions. To further elucidate the generality, the synthesis of optically active thienoindoles, as well as selenophenes, is also demonstrated.
Isoquinoline-based chiral monodentate N-heterocyclic carbenes
Hirsch-Weil, Dimitri,Abboud, Khalil A.,Hong, Sukwon
supporting information; experimental part, p. 7525 - 7527 (2010/12/18)
C1-symmetric isoquinoline-based chiral diaminocarbene ligands (MIQ) have been developed to block three quadrants of the metal coordination sphere, complementing C2-symmetric biisoquinoline-based ligands (BIQ). MIQ-Cu complexes catalyzed conjugate borylation of various α,β-unsaturated amides in good yields (82-99%) and enantioselectivities (75-87% ee).
Copper-Catalyzed conjugate addition of diboron reagents to α,β-unsaturated amides: Highly reactive copper-1,2- bis(diphenylphosphino)benzene catalyst system
Chea, Heesung,Sim, Hak-Suk,Yun, Jaesook
scheme or table, p. 855 - 858 (2009/10/25)
An efficient copper catalyst system for the β-boration of α,β-unsaturated amides has been developed. Copper-bisphosphine complexes with small bite angles generate efficient catalyst systems for the successful conjugate addition of bis(pinaco-lato)diboron
Amide enolate additions to acylsilanes: In situ generation of unusual and stereoselective homoenolate equivalents
Lettan II, Robert B.,Galliford, Chris V.,Woodward, Chase C.,Scheidt, Karl A.
supporting information; experimental part, p. 8805 - 8814 (2009/12/04)
The synthesis of β-hydroxy carbonyl compounds is an important goal due to their prevalence in bioactive molecules. A novel approach to construct these structural motifs involves the multicomponent reaction of acylsilanes, amides, and electrophiles. The ad
Synthesis of tertiary β-hydroxy amides by enolate additions to acylsilanes
Lettan II, Robert B.,Reynolds, Troy E.,Galliford, Chris V.,Scheidt, Karl A.
, p. 15566 - 15567 (2007/10/03)
The synthesis of tertiary β-hydroxy amides from acylsilanes, acetamides, and electrophiles is described. The addition of amide enolates to acylsilanes generates β-silyloxy homoenolate reactivity by undergoing a 1,2-Brook rearrangement. These unique nucleo
Cerium(III) amide enolate. Addition to aldehydes and ketones
Shang,Liu
, p. 2485 - 2489 (2007/10/02)
The cerium(III) amide enolates, prepared in situ from the corresponding lithium enolates and anhydrous CeCl3, were found to undergo facile additions to ketones and aldehydes. Yields of the adducts are superior to those obtained using the lithiu
