ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

Novel iridium complexes containing phenylpyridine and pyridyl aza-benzo fused ligands are described. The complexes are useful as light emitters when incorporated into OLEDs.

PARTIES TO A JOINT RESEARCH AGREEMENT

FIELD OF THE INVENTION

The present invention relates to iridium complexes containing aza-benzo fused ligands. In particular, iridium complexes containing both phenylpyridine ligands and aza-benzo fused ligands were found to be useful as emitters when used in OLED devices.

BACKGROUND

SUMMARY OF THE INVENTION

A compound having the formula Ir(LA)n(LB)3-n, and having the structure:

with Formula I is provided. In the compound of Formula I, A1, A2, A3, A4, A5, A6, A7, and A8 comprise carbon or nitrogen, and at least one of A1, A2, A3, A4, A5, A6, A7, and A8 is nitrogen. Ring B is bonded to ring A through a C—C bond, the iridium is bonded to ring A through a Ir—C bond. X is O, S, or Se. R1, R2, R3, and R4 independently represent mono-, di-, tri-, tetra-substitution, or no substitution, and any adjacent substitutions in R1, R2, R3, and R4 are optionally linked together to form a ring. R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and n is an integer from 1 to 3.

In one aspect, n is 1. In one aspect, the compound has the formula:

In one aspect, the compound has the formula:

In one aspect, only one of A1 to A8 is nitrogen. In one aspect, only one of A5 to A8 is nitrogen. In one aspect, X is O.

In one aspect, R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, alkyl, and combinations thereof. In one aspect, R2 is alkyl.

In one aspect, the alkyl is deuterated or partially deuterated. In one aspect, R3 is alkyl.

In one aspect, the alkyl is deuterated or partially deuterated.

In one aspect, LA is selected from the group consisting of:

In one aspect, LA is selected from the group consisting of:

In one aspect, LB is selected from the group consisting of:

In one aspect, the compound is selected from the group consisting of:

In one aspect, a first device is provided. The first device comprises a first organic light emitting device, further comprising, an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound having the formula Ir(LA)n(LB)3-n, having the structure:

with Formula I is provided. In the compound of Formula I, A1, A2, A3, A4, A5, A6, A7, and A8 comprise carbon or nitrogen, and at least one of A1, A2, A3, A4, A5, A6, A7, and A8 is nitrogen. Ring B is bonded to ring A through a C—C bond, the iridium is bonded to ring A through a Ir—C bond. X is O, S, or Se. R1, R2, R3, and R4 independently represent mono-, di-, tri-, tetra-substitution, or no substitution, and any adjacent substitutions in R1, R2, R3, and R4 are optionally linked together to form a ring. R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and n is an integer from 1 to 3.

In one aspect, the first device is a consumer product.

In one aspect, the first device is an organic light-emitting device.

In one aspect, the first device comprises a lighting panel.

In one aspect, the organic layer is an emissive layer and the compound is an emissive dopant.

In one aspect, the organic layer is an emissive layer and the compound is a non-emissive dopant.

In one aspect, the organic layer further comprises a host.

In one aspect, the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan, wherein any substituent in the host is an unfused substituent independently selected from the group consisting of CnH2n+1, OCnH2n+1, OAr1, N(CnH2n+1)2, N(Ar1)(Ar2), CH═CH—CnH2n+1, C≡CHCnH2n+1, Ar1, Ar1—Ar2, CnH2n—Ar1, or no substitution, wherein n is from 1 to 10; and wherein Ar1 and Ar2 are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In one aspect, the host comprises at least one chemical group selected from the group consisting of carbazole, dibenzothiphene, dibenzofuran, dibenzoselenophene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

In one aspect, the host is selected from the group consisting of:

and combinations thereof.

In one aspect, the host comprises a metal complex.

DETAILED DESCRIPTION

FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, a cathode 160, and a barrier layer 170. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230, device 200 may be referred to as an “inverted” OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one example of how some layers may be omitted from the structure of device 100.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group, and heteroaryl are known to the art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein by reference.

A compound having the formula Ir(LA)n(LB)3-n, and having the structure:

with Formula I is provided. In the compound of Formula I, A1, A2, A3, A4, A5, A6, A7, and A8 comprise carbon or nitrogen, and at least one of A1, A2, A3, A4, A5, A6, A7, and A8 is nitrogen. Ring B is bonded to ring A through a C—C bond, the iridium is bonded to ring A through a Ir—C bond. X is O, S, or Se. R1, R2, R3, and R4 independently represent mono-, di-, tri-, tetra-substitution, or no substitution, and any adjacent substitutions in R1, R2, R3, and R4 are optionally linked together to form a ring. R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and n is an integer from 1 to 3.

Heteroleptic iridium complexes with 2-phenylpyridine and 2-(4-dibenzofuran)-pyridine ligands have been previously disclosed. The dibenzofuran substitution extends the conjugation of the ligand and lowers the LUMO of the complex, resulting in a slight red shifted emission and less saturated green color. For example, Compound A has a λmax of 528 nm in 2-methyl-tetrahydrofuran at room temperature, compared to around 516 nm for tris(2-phenylpyridine)iridium. The compounds of Formula I introduce an azadibenzofuran substitution, as in, for example, Compound 1, which further lowers the LUMO of the complex due to the electron deficient nature of the azadibenzofuran group. The reduction potential was measured at −2.55 V versus −2.60 V for Compound A. Based on these results, it was expected that the emission of Compound 1 will be further red shifted. Surprisingly, the PL of compounds of Formula I such as Compound 1, measured under the same condition as Compound A, showed a λmax of 523 nm, which is 5 nm blue shifted compared to Compound A. Similarly, the ∥max of Compound 4 is 524 nm which is 4 nm blue shifted compared to Compound A. The results are summarized in Table 1. Thus, compounds of Formula I unexpectedly have blue shifted emission spectra, which makes compounds of Formula I more suitable for use as a saturated green color in display applications.

Redox

Compound
Structure
Fc/Fc+
PL in 2-methyl-THF

Compound A

In one embodiment, n is 1. In one embodiment, the compound has the formula:

In one embodiment, the compound has the formula:

In one embodiment, only one of A1 to A8 is nitrogen. In one embodiment, only one of A5 to A8 is nitrogen. In one embodiment, X is O.

In one embodiment, R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, alkyl, and combinations thereof. In one embodiment, R2 is alkyl.

In one embodiment, the alkyl is deuterated or partially deuterated. In one embodiment, R3 is alkyl.

In one embodiment, the alkyl is deuterated or partially deuterated.

In one embodiment, LA is selected from the group consisting of:

In one embodiment, LA is selected from the group consisting of:

In one embodiment, LB is selected from the group consisting of:

In one embodiment, the compound of formula Ir(LA)(LB)2 has the formula:

Compound Number
LA
LB

In one embodiment, the compound is selected from the group consisting of:

In one embodiment, a first device is provided. The first device comprises a first organic light emitting device, further comprising, an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound having the formula Ir(LA)n(LB)3-n, having the structure:

with Formula I is provided. In the compound of Formula I, A1, A2, A3, A4, A5, A6, A7, and A8 comprise carbon or nitrogen, and at least one of A1, A2, A3, A4, A5, A6, A7, and A8 is nitrogen. Ring B is bonded to ring A through a C—C bond, the iridium is bonded to ring A through a Ir—C bond. X is O, S, or Se. R1, R2, R3, and R4 independently represent mono-, di-, tri-, tetra-substitution, or no substitution, and any adjacent substitutions in R1, R2, R3, and R4 are optionally linked together to form a ring. R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and n is an integer from 1 to 3.

In one embodiment, the first device is a consumer product.

In one embodiment, the first device is an organic light-emitting device.

In one embodiment, the first device comprises a lighting panel.

In one embodiment, the organic layer is an emissive layer and the compound is an emissive dopant.

In one embodiment, the organic layer is an emissive layer and the compound is a non-emissive dopant.

In one embodiment, the organic layer further comprises a host.

In one embodiment, the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan, wherein any substituent in the host is an unfused substituent independently selected from the group consisting of CnH2n+1, OCnH2n+1, OAr1, N(CnH2n+1)2, N(Ar1)(Ar2), CH═CH—CnH2n+1, C≡CHCnH2n+1, Ari, Ari-Ar2, CnH2n—Ar1, or no substitution, wherein n is from 1 to 10; and wherein Ar1 and Ar2 are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

In one embodiment, the host comprises at least one chemical group selected from the group consisting of carbazole, dibenzothiphene, dibenzofuran, dibenzoselenophene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

In one embodiment, the host is selected from the group consisting of:

and combinations thereof.

In one embodiment, the host comprises a metal complex.

Device Examples

All example devices were fabricated by high vacuum (<10−7 Torr) thermal evaporation. The anode electrode is 1200 Å of indium tin oxide (ITO). The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al. All devices are encapsulated with a glass lid sealed with an epoxy resin in a nitrogen glove box (<1 ppm of H2O and O2) immediately after fabrication, and a moisture getter was incorporated inside the package.

The organic stack of the device examples consisted of sequentially, from the ITO surface, 100 Å of Compound B as the hole injection layer (HIL), 300 Å of 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (I-NPD) as the hole transporting layer (HTL), 300 Å of the compound of Formula I doped in with Compound C as host, with 10-15 wt % of the iridium phosphorescent compound as the emissive layer (EML), 50 Å of Compound C as a blocking layer (BL), 400 or 450 Å of Alq (tris-8-hydroxyquinoline aluminum) as the ETL. The comparative Example with Compound A was fabricated similarly to the Device Examples except that Compound A was used as the emitter in the EML.

The device results and data are summarized in Tables 2 and 3 from those devices. As used herein, NPD, Alq, and comparative Compounds A to D have the following structures:

device Structures of Inventive Compound and Comparative Compound

HIL
HTL
EML
BL
ETL

Comparative
Compound B
NPD
Compound C
Compound A
Compound C
Alq

Inventive
Compound B
NPD
Compound C
Compound 1
Compound C
Alq

Comparative
Compound B
NPD
Compound C
Compound D
Compound C
Alq

Inventive
Compound B
NPD
Compound C
Compound 105
Compound C
Alq

Inventive
Compound B
NPD
Compound C
Compound 4
Compound C
Alq

VTE Device Results

Table 2 summarizes the performance of the devices. The driving voltage (V), luminous efficiency (LE), external quantum efficiency (EQE) and power efficiency (PE) were measured at 1000 nits. LT80 was measured under a constant current density of 40 mA/cm2 from the initial luminance (L0).

As can be seen from the table, the EL peak of Compound 1 was at 526 nm, which is 4 nm blue shifted compared to that of Compound A. This is also consistent with the PL spectra. Both compounds showed very narrow FWHMs (full width at half maximum) at 60 and 62 nm, respectively. Both compounds showed high EQE in the same structure. The driving voltage of Compound 1 at 1000 nits is slightly lower than that of compound A, 5.9 V vs. 6.2 V. Devices incorporating compounds of Formula I, such as Compound 1, also had longer device lifetimes than devices that used Compound A (184 h vs. 121 h). Compound 4 also displayed a 2 nm blue shift relative to Compound A (528 vs. 530 nm). Additionally the LT80 of Compound 4 is significantly longer than that of Compound A (370 vs. 121 h). Compound 105 was also blue shifted compared to Comparative Compound D (514 nm vs. 520 nm). The color of Compound 105 was also more saturated. Compounds of Formula I have unexpected and desirable properties for use as saturated green emitters in OLEDs.

COMBINATION WITH OTHER MATERIALS

In one aspect, Ar1 to Ar9 is independently selected from the group consisting of:

Examples of metal complexes used in HIL or HTL include, but not limit to the following general formula:

Met is a metal; (Y101-Y102) is a bidentate ligand, Y101 and Y102 are independently selected from C, N, O, P, and S; L101 is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, (Y101-Y102) is a 2-phenylpyridine derivative.

In another aspect, (Y101-Y102) is a carbene ligand.

In another aspect, Met is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc*/Fc couple less than about 0.6 V.

Met is a metal; (Y103-Y104) is a bidentate ligand, Y103 and Y104 are independently selected from C, N, O, P, and S; L101 is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, the metal complexes are:

In another aspect, Met is selected from Ir and Pt.

In a further aspect, (Y103-Y104) is a carbene ligand.

In one aspect, host compound contains at least one of the following groups in the molecule:

k is an integer from 1 to 20; k′″ is an integer from 0 to 20.

X101 to X108 is selected from C (including CH) or N.

Z101 and Z102 is selected from NR101, O, or S.

A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED.

k is an integer from 1 to 20; L101 is another ligand, k′ is an integer from 1 to 3.

Ar1 to Ar3 has the similar definition as Ar's mentioned above.

k is an integer from 1 to 20.

X101 to X108 is selected from C (including CH) or N.

In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exciton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table 4 below. Table 4 lists non-limiting classes of materials, non-limiting examples of compounds for each class, and references that disclose the materials.

MATERIAL
EXAMPLES OF MATERIAL
PUBLICATIONS

Hole injection materials

Phthalocyanine and porphryin compounds

Phosphonic acid and slime SAMs

Triarylamine or polythiophene polymers with conductivity dopants

Organic compounds with conductive inorganic compounds, such as molybdenum and tungsten oxides

Metal organometallic complexes

Polythiophene based polymers and copolymers

Hole transporting materials

Metal carbene complexes

Phosphorescent OLED host materials

Red hosts

Metal phenoxybenzothiazole compounds

Aromatic fused rings

Zinc complexes

Chrysene based compounds

Green hosts

Donor acceptor type molecules

Metal phenoxybenzooxazole compounds

Metal phenoxypyridine compounds

Blue hosts

Silicon aryl compounds

Carbazole linked by non-conjugated groups

High triplet metal organometallic complex

Red dopants

Green dopants

and its derivatives

Monomer for polymeric metal organometallic compounds

Cu complexes

Gold complexes

Organometallic complexes with two or more metal centers

Blue dopants

Gold complexes

Pt tetradentate complexes with at least one metal- carbene bond

Exciton/hole blocking layer materials

Fluorinated aromatic compounds

Electron transporting materials

Bathocuprine compounds such as BCP, BPhen, etc

Fluorinated aromatic compounds

Experimental

Chemical abbreviations used throughout the text are as follows: DME is dimethoxyethane, THF is tetrahydrofuran, DCM is dichloromethane, DMSO is dimethyl sulfoxide, dba is dibenzylidineacetone.

Synthesis of Compound 1

Preparation of 2-(3-bromopyridin-2-yl)-6-chlorophenol

(3-Chloro-2-hydroxyphenyl)boronic acid (5.0 g, 29.0 mmol) and 2,3-dibromopyridine (6.87 g, 29.0 mmol) were added to a 500 mL 2-necked flask. The reaction mixture was diluted with DME (120 mL) and water (90 mL) with the potassium carbonate (8.02 grams, 58.0 mmol) dissolved in it. This mixture was degassed for 10 minutes before addition of Pd(PPh3)4 (1.00 grams, 3 mol %). The reaction mixture was then stirred at gentle reflux for 5 hours. The reaction mixture was then diluted with ethyl acetate and brine. The organic layer was washed with brine and dried over sodium sulfate. The product was purified using silica gel column chromatography using a mobile phase gradient of 5-10% ethyl acetate in hexane to obtain 2.8 grams (34%) of a white solid.

Preparation of 6-chlorobenzofuro[3,2-b]pyridine.

Into a 500 mL round-bottomed flask was placed 2-(3-bromopyridin-2-yl)-6-chlorophenol (4.5 g, 15.82 mmol), copper(I) iodide (0.602 g, 3.16 mmol), picolinic acid (0.779 g, 6.33 mmol) and potassium phosphate (6.71 g, 31.6 mmol in DMSO (150 mL). This mixture was stirred in an oil bath at 125° C. for 5 hours. The heat was removed and the mixture was diluted with ethyl acetate and filtered through Celite®. The filtrate was washed with brine twice then with water. The organic layer was adsorbed onto Celite® and chromatographed eluting with 40-100% dichloromethane in hexane to obtain 2.45 grams (76%) of a white solid.

Preparation of 6-(pyridin-2-yl)benzofuro[3,2-b]pyridine.

Preparation of Compound 1

Synthesis of Compound 4

Preparation of 3-(2,3-dimethoxyphenyl)pyridin-2-amine

3-Bromopyridin-2-amine (23.77 g, 137 mmol), (2,3-dimethoxyphenyl)boronic acid (25 g, 137 mmol), and Pd(Ph3P)4 (4.76 g, 4.12 mmol) were added to a 2 L 2-necked flask. The reaction mixture was diluted with THF (600 mL). A solution of water (300 mL) with sodium carbonate (14.56 g, 137 mmol) dissolved in it was then added. This mixture was degassed and stirred at reflux for 20 hours. The mixture was then diluted with ethyl acetate and brine. The organic layer was washed with water and dried over sodium sulfate. The product was chromatographed on a silica gel column eluted with 0-50% ethyl acetate in DCM to obtain 28.9 g (91%) of the desired material.

Preparation of 8-methoxybenzofuro[2,3-b]pyridine

3-(2,3-Dimethoxyphenyl)pyridin-2-amine (14 g, 60.8 mmol) was added to a 500 mL round bottom flask. Acetic acid (220 mL) and THF (74 mL) were added. This mixture was stirred in a salt water ice bath. t-Butyl nitrite (14.5 mL, 109 mmol) was added drop-wise. The reaction mixture was stirred in the bath for 3 hours and then was allowed to warm ambient temperature with stirring. This mixture was evaporated in vacuo and partitioned between ethyl acetate and aqueous sodium bicarbonate. The product was chromatographed on silica gel. Elution with 25% ethyl acetate in hexane gave 6.61 g (54.6%) of 8-methoxybenzofuro[2,3-b]pyridine as a white solid.

Preparation of benzofuro[2,3-b]pyridin-8-ol

8-Methoxybenzofuro[2,3-b]pyridine (6.6 g, 33.1 mmol) was added along with pyridine HCl (25 g) to a 250 mL round bottom flask. This mixture was stirred in an oil bath at 200° C. for 10 hous. Aqueous sodium bicarbonate and DCM were added to the mixture. The organic layer was dried and evaporated to a brown solid to obtain 5.07 g (83%) of the desired.

Preparation of benzofuro[2,3-b]pyridin-8-yl trifluoromethanesulfonate

Benzofuro[2,3-b]pyridin-8-ol (5.5 g, 29.7 mmol) was added to a 500 mL round bottom flask and DCM (250 mL) was added. Pyridine (6.01 mL, 74.3 mmol) was added and the flask was placed in an ice bath. Triflic anhydride (7.5 mL, 44.6 mmol) was dissolved in DCM (30 mL) and added drop-wise over 10 min. The bath was removed and the reaction was allowed to warm to ambient temperature and stirred overnight. The solution was washed with saturated sodium bicarbonate solution then water. The product was chromatographed on a silica gel column, which was eluted with DCM to obtain 8.1 g (86%) of the desired product as a white solid was obtained.

Preparation of 8-(pyridin-2-yl)benzofuro[2,3-b]pyridine

Benzofuro[2,3-b]pyridin-8-yl trifluoromethanesulfonate (4 g, 12.61 mmol), X-Phos (0.481 g, 1.009 mmol) and Pd2dba3 (0.231 g, 0.252 mmol) were added to a 250 mL 3-necked flask. The atmosphere in the flask was evacuated and backfilled with nitrogen. THF (40 mL) and pyridin-2-yl zinc(II) bromide (37.8 mL, 18.91 mmol) were added. This mixture was stirred in an oil bath at 70° C. for 4 hours. The mixture was filtered through Celite®, and the filter cake was washed with ethyl acetate. The crude material was adsorbed on to Celite® and chromatographed on a silica gel column eluted with 25-50% ethyl acetate in hexane to obtain 2.7 g (87%) of the desired product as a white solid.

Preparation of Compound 4

8-(Pyridin-2-yl)benzofuro[2,3-b]pyridine (3.8 g, 15.4 mmol) and iridium complex (3.67 g, 5.10 mmol) were combined in a 500 mL round bottom flask. 2-Ethoxyethanol (125 mL) and dimethylformamide (125 mL) were each added and the mixture was stirred in an oil bath at 135° C. for 18 hours. The mixture was concentrated first on a rotary evaporator then on a Kugelrohr apparatus. The residue was purified on a silica gel column eluted with 0-3% ethyl acetate in dichloromethane to afford 2.48 g (65%) of the desired product as yellow solid.

Synthesis of Compound 105

Preparation of 2-(5-chloro-2-methoxyphenyl)pyridin-3-amine

Preparation of 8-chlorobenzofuro[3,2-b]pyridine

In a 1 L round-bottomed flask was placed 2-(5-chloro-2-methoxyphenyl)pyridin-3-amine (10.9 g, 46.4 mmol) and THF (85 mL). Tetrafluoroboric acid (85 mL, 678 mmol) was added along with water (50 mL). The flask was placed in an ethylene glycol-dry ice bath. Sodium nitrite (6.73 g, 98 mmol) was dissolved water (30 mL) and added drop-wise to the flask. The solution turned from yellow to orange with evolution of gas. This reaction mixture was stirred in the bath for 4 hours, and allowed to warm to ambient temperature. Aqueous saturated sodium bicarbonate (500 mL) was added. The product was extracted with DCM and chromatographed on a 200 gram silica gel column eluted with 20-40% ethyl acetate in hexane to obtain 3.26 g (34.5%) of the desired product as a white solid.

Preparation of 8-(pyridin-2-yl)benzofuro[3,2-b]pyridine

Preparation of Compound 105

Iridium complex (2.99 g, 4.20 mmol) and 8-(pyridin-2-yl)benzofuro[3,2-b]pyridine (3.1 g, 12.59 mmol) were each added to a 250 mL round bottom flask. 2-Ethoxyethanol (50 mL) and dimethylformamide (50 mL) were added and this was stirred in an oil bath at 150° C. for 18 hours. The flask was placed on a Kugelrohr apparatus and the solvents were removed. The crude material was chromatographed on a silica gel column eluted with 0-10% ethyl acetate in DCM to obtain 2.07 g (66%) of the desired compound.