Supporting Information Synthesis of H-Indazoles from Imidates and Nitrosobenzenes via Synergistic Rhodium/Copper Catalysis Qiang Wang and Xingwei Li* Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China *email: xwli@dicpaccn Table of Contents General information S Experimental procedures S Mechanistic studies S Characterization data S NMR spectra S S
General Information All reactions were carried out using oven dried glassware unless otherwise noted All solvents were purchased from commercial sources and were used as received NMR spectra were recorded at K on a Bruker Advance Ultrashield apparatus H NMR and C NMR spectra were recorded with the chemical shifts (δ) given in ppm relative to TMS Coupling constants (J) were reported in Hz All compounds purified by chromatography were sufficiently pure for use in further experiments, unless otherwise indicated Experimental Procedures Synthesis of Imidate Ester According to a literature report, alcohol ( mmol) and aryl nitrile ( mmol) were stirred in a round bottom flask Then AcCl ( mmol) was added dropwise within minutes in an ice bath The reaction mixture was stirred at room temperature for h, and the solvent was removed under reduced pressure to give a white solid The white solid was washed with Et O, and saturated NaHCO solution was then added till gas evolution ceased The resulting mixture was extracted with EtOAc three times The organic layers were collected and concentrated under reduced pressure to give the desired product Synthesis of nitrosobenzene According to a literature report, an aniline ( mmol) was dissolved in DCM ( ml), then the solution of oxone ( mmol, g) in ml water was added slowly The reaction mixture was stirred at room temperature till full consumption of the starting material as monitored by TLC Then the reaction mixture was separated and extracted with EtOAc twice The combined organic layers were washed with M HCl then saturated Na CO and brine After dried by anhydrous Na SO, the solvent was evaporated, and the crude mixture was purified by flash column chromatography on silica gel to afford analytically pure nitrosobenzene General procedure of the synthesis of H-indazoles A pressure tube was charged with [Cp * Rh(MeCN) ](SbF ) ( mol %, g), CuCl ( mol %, g), imidate (, mmol), notrosobenzene (, mmol), A MS ( g), and trifluorotoluene ( ml) The mixture was stirred at o C under N for h Then the solvent was evaporated and the crude residue was purified by flash column chromatography to give the desired product Yield of the indazole product with different amounts of nitrosobenzene Reaction was carried out in the scale of mmol of under the standard conditions with a variable amount of nitrosobenzene The yield refers to isolated yield S
Mechanistic studies KIE experiment A mixture of a ( mmol), a-d ( mmol), nitrosobenzene ( mmol), [Cp * Rh(MeCN) ](SbF ) ( mol %), CuCl ( mol %,), and A MS ( g) was stirred at o C for h The crude product was purified by column chromatography The KIE value was determined by the H NMR analysis of the isolated mixture f (ppm) S
k H /k D = / The preparation of rhodium complex An oven-dried Schlenk tube was charged with imidate a ( mmol, g), [Cp * RhCl ] ( mmol, g), NaOAc ( mmol, g) and DCE ( ml), the reaction mixture was stirred at o C under N for h After filtration of the mixture under N atmosphere, the filtrate was concentrated under vacuum The final product was obtained after recrystallization using Et O Yield: % H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (dd, J =, Hz, H), (t, J = Hz, H), (m, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ (d, J = Hz),,,,,,, (d, J = Hz),,, HRMS (ESI): calcd for C H NORh (M-Cl), found Crystal structure of Table S Crystal data and structure refinement for cd Identification code cd Empirical formula C H ClNORh Formula weight Temperature () K Wavelength Å Crystal system Monoclinic Space group P/c Unit cell dimensions a = () Å α = b = () Å β = () S
c = () Å γ = Volume () Å Z Density (calculated) Mg/m Absorption coefficient mm - F() Crystal size x x mm Theta range for data collection to Index ranges Reflections collected -<=h<=, -<=k<=, -<=l<= Independent reflections [R(int) = ] Completeness to theta = % Absorption correction Semi-empirical from equivalents Max and min transmission and Refinement method Full-matrix least-squares on F Data / restraints / parameters / / Goodness-of-fit on F Final R indices [I>sigma(I)] R =, wr = R indices (all data) R =, wr = Extinction coefficient n/a Largest diff peak and hole and - eå - Coupling of a and a catalyzed by complex Complex ( mol %, g) and AgSbF ( mol %) were added to trifluorotoluene ( ml) in an oven-dried tube The reaction mixture was stirred for minutes at o C, then a ( mmol, g), a ( mmol, g), CuCl ( mol%, g), and A MS (g) were added The tube was placed into a o C oil bath for h The pure product was obtained from standard purification in % yield Rh(III)/Cu(I) catalyzed the synthesis of H-Indazole A pressure tube was charged with [Cp * Rh(MeCN) ](SbF ) ( mol %, g), CuCl ( mol %, g), imidate a ( g, mmol), nitrosobenzene a ( g, mmol), A MS ( g) and trifluorotoluene ( ml) The mixture was stirred and heated at o C for h Then the solvent was evaporated and the residue was purified by flash column chromatography to give a in % yield S
Competition experiment A competition reaction was performed using a mixture of c ( mmol) and j ( mmol) as substrates following the standard procedure The product ratio was determined by H NMR analysis of the product mixture Rh(III)-catalyzed Amidation of k k ( mmol, g), ( mmol, g), [Cp * RhCl ] ( mol %, g), and AgSbF ( mol %, g) were added to DCE ( ml) in a pressure tube under N atmosphere After stirring for h, the solvent was evaporated and the residue was purified by silica column chromatography (ethyl acetate/petroleum ether = /) to afford the product as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (s, H), (d, J = Hz, H), (d, J = Hz, H), (m, H), (m, H), (m, H), (dd, J =, Hz, H), (q, J = Hz, H), (m, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,,,,,,,,, HRMS (ESI): calcd for S
C H N O ([M+H] + ), found References () Yadav, V; Babu, K Eur J Org Chem,, - () Beate Priewisch, Karola Rǜck-Braun, J Org Chem,, - Characterization Data -Ethoxy--phenyl-H-indazole a was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (dd, J =, Hz, H), (dd, J =, Hz, H), (d, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (dd, J =, Hz, H), (t, J = Hz, H), (m, H), (td, J =, Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--methyl--phenyl-H-indazole b was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (m, H), (t, J = Hz, H), (d, J = Hz, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--methoxy--phenyl-H-indazole c was obtained via silica gel S
column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (d, J = Hz, H), (dd, J =, Hz, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found,-diethoxy--phenyl-h-indazole d was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (m, H), (d, J = Hz, H), (dd, J =, Hz, H), (dd, J =, Hz, H), (d, J = Hz, H), (dd, J =, Hz, H), (q, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--fluoro--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (m, H), (m, H), (ddd, J =,, Hz, H), (td, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ (d, J = Hz),,,,,, (d, J = Hz),,, (d, J = Hz), (d, J = Hz),, F NMR ( MHz, CDCl ) δ - HRMS (ESI): calcd for C H FN O ([M+H] + ), found -Chloro--ethoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a yellow solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (dd, J =, Hz, H), (t, J = Hz, H), (dd, J =, Hz, H), (dd, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,, S
,,,, HRMS (ESI): calcd for C H ClN O ([M+H] + ), found -Bromo--ethoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a yellow solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (dd, J =, Hz, H), (d, J = Hz, H), (dd, J =, Hz, H), (t, J = Hz, H), (dd, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H BrN O ([M+H] + ), found -Ethoxy--iodo--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (s, H), (d, J = Hz, H), (m, H), (d, J = Hz, H), (t, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H IN O ([M+H] + ), found Ethyl--ethoxy--phenyl-H-indazole--carboxylate was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (s, H), (m, H), (d, J = Hz, H), (t, J = Hz, H), (dd, J =, Hz, H), (q, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found S
-(-Ethoxy--phenyl-H-indazol--yl)ethanone was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (s, H), (d, J = Hz, H), (m, H), (t, J = Hz, H), (t, J = Hz, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy-,-dimethyl--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (m, H), (t, J = Hz, H), (q, J = Hz, H), (s, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--methyl--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (d, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--methoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a yellow oil ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (dd, J =, Hz, H), (t, J = Hz, H), (dd, J =, Hz, H), (m, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,, S
,,,,,,,,, RMS (ESI): calcd for C H N O ([M+H] + ), found -Ethoxy--fluoro--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (dd, J =, Hz, H), (m, H), (m, H), (dd, J =, Hz, H), (m, H), (td, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ (d, J= Hz), (d, J = Hz),,,,,, (d, J = Hz), (d, J = Hz), (d, J = Hz), (d, J = Hz),, F NMR ( MHz, CDCl ) δ - HRMS (ESI): calcd for C H FN O ([M+H] + ), found -Ethoxy--fluoro--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (dd, J =, Hz, H), (m, H), (d, J = Hz, H), (m, H), (dd, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ (d, J = Hz), (d, J = Hz), (d, J = Hz),,, (d, J = Hz),,, (d, J = Hz), (d, J = Hz), (d, J = Hz),, F NMR ( MHz, CDCl ) δ - HRMS (ESI): calcd for C H FN O ([M+H] + ), found -Methoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (m, H), (dd, J =, Hz, H), (ddd, J =,, Hz, H), (t, J = Hz, H), (t, J = Hz, H), (s, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found S
-Phenyl--propoxy-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (m, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (h, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Isopropoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (s, H), (d, J = Hz, H), (dd, J =, Hz, H), (m, H), (t, J = Hz, H), (t, J = Hz, H), (dt, J =, Hz, H), (d, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -Butoxy--phenyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (m, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (m, H), (m, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found,-diphenyl-h-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a pale yellow solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (m, H), m, H), (m, H), (m, H), (t, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,, S
,,,,,,,,,, HRMS (ESI): calcd for C H N ([M+H] + ), found Ethyl--(phenylamino)benzoate was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a yellow oil ( mg, % yield) H NMR ( MHz, CDCl ) δ (s, H), (d, J = Hz, H), (t, J = Hz, H), (d, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H NO ([M+H] + ), found -(-tert-butylphenyl)--ethoxy-h-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (d, J = Hz, H), (d, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H), (s, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -(-Chlorophenyl)--ethoxy-H-indole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (m, H), (m, H), (dd, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H ClNO ([M+H] + ), found S
-(-Bromophenyl)--ethoxy-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (m, H), (ddd, J =,, Hz, H), (t, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H BrN O ([M+H] + ), found, -Ethoxy--(-nitrophenyl)-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a yellow solid ( mg, % yield) H NMR ( MHz, CD Cl ) δ (m, H), (dt, J =, Hz, H), (td, J =, Hz, H), (m, H), (dd, J =, Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CD Cl ) δ,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found Ethyl--(-ethoxy-H-indazol--yl)benzoate was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (m, H), (m, H), (d, J = Hz, H), (m, H), (t, J = Hz, H), (q, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found S
-Ethoxy--m-tolyl-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid (mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (d, J = Hz, H), (m, H), (t, J = Hz, H), (d, J = Hz, H), (q, J = Hz, H), (s, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -(,-Dimethylphenyl)--ethoxy-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as a white solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (dd, J =, Hz, H), (dd, J =, Hz, H), (s, H), (t, J = Hz, H), (m, H), (m, H), (qd, J =, Hz, H), (s, H), (s, H), (td, J =, Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,,,, HRMS (ESI): calcd for C H N O ([M+H] + ), found -(,-Dichlorophenyl)--ethoxy-H-indazole was obtained via silica gel column chromatography (petroleum ether/ethyl acetate = /, v/v) as yellow solid ( mg, % yield) H NMR ( MHz, CDCl ) δ (d, J = Hz, H), (d, J = Hz, H), (d, J = Hz, H), (dd, J =, Hz, H), (d, J = Hz, H), (m, H), (t, J = Hz, H), (q, J = Hz, H), (t, J = Hz, H) C NMR ( MHz, CDCl ) δ,,,,,,,,,,,,,, S
HRMS (ESI): calcd for C H Cl N O ([M+H] + ), found S
S NMR Spectra - - - f (ppm) - f (ppm)
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S - f (ppm) - - f (ppm) N OEt Cl b
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