60081-02-9

Upstream product

• 17318-03-5 bromo(3-fluorophenyl)magnesium 
• 6630-33-7 ortho-bromobenzaldehyde 
• 1073-06-9 3-fluorobromobenzene 

Downstream Products

• 343-43-1 2-fluoro-9H-fluorene 
• 317-71-5 4-fluoro-9H-fluorene 

Relevant academic research and scientific papers

Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation

Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.

Au-catalyzed biaryl coupling to generate 5- to 9-membered rings: Turnover-limiting reductive elimination versus π-complexation

The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes-substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to π-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the π-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.

Au-Catalyzed Biaryl Coupling to Generate 5- To 9-Membered Rings: Turnover-Limiting Reductive Elimination versus ?-Complexation

The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes - substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to ?-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the ?-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.

Efficient palladium-catalyzed C(sp2)-H activation towards the synthesis of fluorenes

A facile protocol for the synthesis of fluorene derivatives has been developed through palladium-catalyzed cyclization of 2′-halo-diarylmethanes via activation of arylic C-H bonds. The reactions occurred smoothly and allowed both electron-rich and electron-deficient substrates to convert into their corresponding fluorenes in good to excellent yields. Studies revealed that this Pd-catalyzed cyclization was also available for the substrates of 2′-chloro-diarylmethanes and no catalyst poisoning occurred for 2′-iodo-diphenylmethane.

Bismuth-catalyzed synthesis of anthracenes via cycloisomerization of o-alkynyldiarylmethane

In this study, anthracenes were efficiently synthesized from o-alkynyldiarylmethane using a novel method that exploits the synergistic effect between Bi(OTf)3 as the catalyst, and trifluoroacetic acid (TFA). Through this reaction, we achieved the rapid and efficient synthesis of anthracenes bearing various functional groups under mild conditions.

Synthesis of spiro[isobenzofuran 1(3H),4' piperidines] as potential central nervous system agents

Synthesis of 1' methyl 3 phenylspiro[isobenzofuran 1(3H),4' piperidine] (7a, HP 365) and the demethyl analogue 9a (HP 505) was prompted by recognition of an aminoalkyl(aryl)isobenzofuran moiety common to the antidepressants talopram (Lu 3-010) and trans 10,11 dihydro 5,10 epoxy 5 [3 (methylamino)propyl] 5H dibenzo[a,d]cyclohepten 11 ol (MK-940). Convenient laboratory synthesis of 7a was provided by lithiation of 2 bromobenzhydryl methyl ether, followed by addition of 1 methyl 4 piperidone and acid catalyzed cyclization. N Dealkylation by standard methods afforded 9a. Synthesis of analogues was stimulated by discovery of marked inhibition of tetrabenazine induced ptosis for lead compounds 7a and 9a. Optimal antitetrabenazine activity is associated with the 3 phenylspiro[isobenzofuran 1(3H),4' piperidine] moiety where nitrogen is basic. Modification of this moiety by introduction of large nitrogen substituents or a C-3 substituent > H significantly reduced antitetrabenazine activity. A series of analogue with aromatic substituents was investigated; however, few of these compounds were significantly more active than 7a and 9a. Compound 9a was selected for additional studies.