Current Literature July 19, 08 Jitendra Mishra Arylhalide-Tolerated Electrophilic Amination of Arylboronic Acids with -Chloroamides Catalyzed by CuCl at Room Temperature Aiwen Lei et.al. College of the Chemistry andmolecular Sciences Wuhan University Wuhan, Hubei, 430072 (PR China) Angew. Chemie. Int. Ed. 2008, Early view Jitendra Mishra@ Wipf Group Page 1 of 20 7/22/2008 1
Introduction Aryl amines are common place in chemistry. Arene-nitrogen or arene-oxygen linkage is included in nitrogen or oxygen heterocycles such as Indole, and benzofurans. Isodityrosine based natural product such as vancomycin. Conjugated polymers such as polyanilines. Readily oxidized triarylamines used in electronic applications such as such as,'-diphenyl-,'-bis(3-methylphenyl)- 1,1'-biphenyl-4,4'-diamine. Jitendra Mishra@ Wipf Group Page 2 of 20 7/22/2008 2
Historical Background: The initial effort for the formation of transition metal mediated C- bond was made by Hartwig et. al. and Buchwald group independently. Br + Bu 3 SnR 2 [(o-ch 3 C 6 H 4 ) 3 P]PdX 2 75-85% R 2 Hartwig et. al. JACS 1994, 5969. Jitendra Mishra@ Wipf Group Page 3 of 20 7/22/2008 3
Br R' R + HRR' L 2 Pd or L 2 PdCl 2 Li(SiMe) 3 30 min. 60 o C Hartwig et. al. TL 1995, 3609 -First tin reagent free Pd catalyzed amination of aryl halide. Jitendra Mishra@ Wipf Group Page 4 of 20 7/22/2008 4
Br R' R R + HRR' L 2 Pd or L 2 PdCl 2 tbuoa 60-100 o C, toluene, 71-89% R X HBn n Cat. Pd aotbu, K 2 CO 3, Toluene, 100 o C, 75-96 % n Bn n = 1-3 Buchwald et. al. Angew. Chem. Int. Ed. 1995, 1348 Jitendra Mishra@ Wipf Group Page 5 of 20 7/22/2008 5
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H 2 COOH + ArX CuI K 2 CO 3, DMA, 5-92% H COOH Possible catalytic cycle Dawai Ma et. al. JACS 1998, 12459 7 Jitendra Mishra@ Wipf Group Page 7 of 20 7/22/2008
CuSO 4, Cu(OAc) 2, CuI, were used as catalysts and gave over 80% yield. The reaction catalyzed by CuI was faster comparision to other. A strong o-carboxylate accelarating effect was observed while p- has no similar effect. The order of halogen displacement from aromatic ring is I > Br > Cl. Amino acid containing larger hydrophobic group gave higher coupling yield compare to lower hydrophobic group and the amino acids with hydrophillic group yielded no coupling product at all. Cyclic amino acid gave higher yield. Jitendra Mishra@ Wipf Group Page 8 of 20 7/22/2008 8
Ar-I + O H R' R 1 mol% CuI, 10 mol% ligand, O 2 eq K 3 PO 4 23h, 110 o C, Dioxane Ar R' R RH Ligand HR R 1 mol% CuI, I + R 2 R 3 10 mol% ligand, 2 eq K 3 PO 4 H 24h, 110 o C, Dioxane, R 65-100% R 3 R 2 1a; R = H 1b; R = Me - -arylation of nitogen heterocycles Buchwald et. al. JACS 2001, 7727. Jitendra Mishra@ Wipf Group Page 9 of 20 7/22/2008 9
O R O H 2 L-amino ester B(OH) 2 Cu(OAc) 2, TEA, 4A o MS, DCM, rt, 1-2 days R H O O Lam et.al. TL 2003, 1691 Jitendra Mishra@ Wipf Group Page 10 of 20 7/22/2008 10
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O H + B(OH) 2 0.1 eq Cu(OAc)2, 1.1 eq oxidant, TEA 4A o MS, DCM, rt, air, 1-2 days O Pyridine-oxide > TEMPO > MO > di-t-butyl nitroxide > (1R) (10-camphor- 69% 64% 62% 55% 48% sulfonyl)oxaziridine > abo 3.H 2 O, > K 3 Fe(C) 6 > mcpba 31% 11% 6% Lam et. al. TL 2001, 3415 Jitendra Mishra@ Wipf Group Page 12 of 20 7/22/2008 12
Ph OR' Ph + Ph B(OH) 2 10 mol% CuCT solvent, Ar, 50 o C, 3h Ph Ph Ph Cross-coupling product + Ph Ph + Homocoupling O Ph Ph Hydrolysis CuCT = Cu(I) thiophene-2-carboxylate Liebeskind et.al. 2007, 1947. Jitendra Mishra@ Wipf Group Page 13 of 20 7/22/2008 13
Ar O + CuCl 1. DMF, 55 o C, 30-40 min. 2. 1.1-1.2 eq Ar'B(OH) 2, DMF, 55 o C, 16h Ar H Ar' Liebeskind et. al. OL. 2004, 2631 Jitendra Mishra@ Wipf Group Page 14 of 20 7/22/2008 14
Title paper: Reasons to Choose -Chloroamides: - Ease of preparation of -Chloroamides. - High activities of -Cl bond. R 1 R 2 H aox/ter-buoh AcOH/MTBE 0 o C, 15 min-2h, 90-100% R 1 R 2 X X = Br, Cl Jitendra Mishra@ Wipf Group Page 15 of 20 7/22/2008 15
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Cu Catalyzed -Phenylation of -chloramide 1a O Ph Cl + PhB(OH) 2 catalyst O base, solvent Ph 2a 25 o C Ph 3a Jitendra Mishra@ Wipf Group Page 17 of 20 7/22/2008 17
R 1 Cl + R 2 (HO) 2 B CuCl (10 mol%) R 3 R a 2 CO 3, THF 25 o C R 2 R 3 Jitendra Mishra@ Wipf Group Page 18 of 20 7/22/2008 18
Ar 1 Cl Ac + (HO) 2 B R CuCl (10 mol%) a 2 CO 3, THF 25 o C Ar 1 Ac R 3 Jitendra Mishra@ Wipf Group Page 19 of 20 7/22/2008 19
Conclusion -The authors utilized easily prepared and highly reactive -chloroamides to develop an efficient copper catalyzed electrophilic amination of arylboronic acids. -The developed methodoly gave high yields of diarylamides and tolerated a wide variety of functional groups, including iodo, bromo, and chloro moieties, which are usually sensitive in palladium-catalyzed reactions. -A scale up experiment was carried out to demonstrate the practicability of the method to provide biaryl amides or amines having sensitive substituents. -The availability of various boronic acids promises highlights the potential of the methodology. - Their preliminary mechanistic studies support the proposed mechanism and the results of additional investigations that are ongoing in their laboratory. Jitendra Mishra@ Wipf Group Page 20 of 20 7/22/2008 20