Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines

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M. Joshi, A. Roychoudhury and K. Ghosh, Dalton Trans., 2021, DOI: 10.1039/D0DT03748F.

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14 March 2017

Pages 3073-3412

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ARTICLE

Designed pincer ligands supported Co(II)-based catalysts for

dehydrogenative activation of alcohols: Studies on N-alkylation of

amines, -alkylation of ketones and synthesis of quinolines

Received 00th January 20xx,

Accepted 00th January 20xx

Anshu Singh^a, Ankur Maji^a, Mayank Joshi^b, Angshuman R. Choudhury^b, and Kaushik Ghosh*^a

DOI: 10.1039/x0xx00000x

Base-metal catalysts Co1, Co2 and Co3 were synthesized from designed pincer ligands L¹, L²and L³having NNN donor atoms

respectively. Co1, Co2 and Co3 were characterized by IR, UV–Vis. and ESI-MS spectroscopic studies. Single crystal X-ray

diffraction studies were investigated to authenticate the molecular structures of Co1 and Co3. Catalysts Co1, Co2 and Co3

were utilized to study the dehydrogenative activation of alcohols for N-alkylation of amines, -alkylation of ketones and

synthesis of quinolines. Under optimized reaction conditions a broad range of substrates including alcohols, anilines and

ketones were exploited. A series of controlled experiments for N-alkylation of amines, -alkylation of ketones and synthesis

of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize

cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was

investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed for N-

alkylation of amines, -alkylation of ketones and synthesis of quinolines on the basis of controlled experiments and

detection of reaction intermediates.

various functional groups.⁶Amines are valuable building blocks for

different fungicides, pesticides, pharmaceuticals, fine chemicals

Introduction

Pincer ligands are meridional tridentate ligands which could binds to

the coplanar sites of a metal center.¹Transition metal based catalysts

derived from pincer ligands received considerable current interest.²

However, catalysts supported by pincer ligands containing NNN

donors received special attention for the dehydrogenative activation

of alcohols and organic transformations.³Earth abundant transition

metals not only offer potential environment but also provide chances

to explore base-metal catalysts and eventually new avenues for

innovations in chemical research.⁴In this regard electronic structures

of base-metal complexes are significantly important for their

catalytic performance.⁵Development of reliable, readily available

base-metal catalysts having effective, atom economical, greener

choice and selective method for CN and CC bond formation have

been exciting endeavour and are vital for organic synthesis with

additives and agrochemicals⁷(Scheme 1). Moreover, it is well known

that nitrogen functionality occurs in various biologically active

molecules and different pharmaceuticals compounds.⁸Hence,

synthesis of amines and development of base-metal catalysts were

found to be an important area in chemical research.⁹There are

reports on Fe,¹⁰Mn,¹¹and Ni¹²-based catalysts. Although, Co^9a,13

-

based catalysts are significantly important for N-alkylation reactions.

On the other hand, -alkylation of ketones via dehydrogenative

activation of alcohols are extremely important in organic syntheses

and synthetic chemistry. Several biologically active compounds and

drug molecules involved in anti-inflammatory, analgesic, anti-

diabetic, antitumor and antibacterial activity were synthesized

utilizing this process (Scheme 1).¹⁴Hence, development of new

methodology and catalysts are important areas of chemical research.

Excluding platinum metal-based catalysts recently, -alkylation of

ketones has been performed by manganese,¹⁵iron,¹⁶copper¹⁷and

cobalt¹⁸based base-metal catalysts.

^aDepartment of Chemistry, Indian Institute of Technology Roorkee, Roorkee-

247667 Uttarakhand, India

^bDepartment of Chemical Sciences, Indian Institute of Science Education and

Research Mohali

E-mail: kaushik.ghosh@cy.iitr.ac.in, ghoshfcy@iitr.ac.in

Electronic

supplementary

information

(ESI)

available:

NMR,

ESI-MS,

and UV-visible spectral data and information on X-ray crystal structure data have been

deposited in the Cambridge Crystallographic Data Centre and the deposition number for

Complex Co1 is CCDC, 2012672 and Complex Co3 is CCDC 2012671 See

DOI: 10.1039/x0xx00000x

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water as a by-product for the synthesis of quinoline.²¹For instance,

N-alkylated

compounds

Alpha-alkylated

compounds

Quinoline

derivatives

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DOI: 10.1039/D0DT03748F

the transition metal complexes of mainly Ru,²²Ir²³and Re²⁴were

O

R

utilized for quinoline synthesis. Now-a-days base-metal complexes

such as Mn,^20cCo²⁵and Ni^20bcomplexes were exploited as catalysts

for synthesis of N-heterocycles. These methods described above for

N-alkylation, -alkylation and quinoline synthesis exhibit

disadvantages of high catalyst loading, phosphorous based ligands

and harsh reaction conditions.

HO

MeO

OMe

Fluoxetine

R= H, Loureirin A

R= OMe Loureirin B

Chloroquine

OMe O

In recent years there is an upsurge of interest for the reactivity of

cobalt complexes derived from pincer ligands having NNN donor

atoms.^3,26,27Cobalt complexes derived from pincer ligands were

utilized for hydroboration,^27ahydrogenation reaction,^27b

isomerization of styrene,^27cpolymerization reaction,^27dwater

reduction²⁸and hydrosilylation reaction.²⁹Further, cobalt complexes

derived from pincer ligands are important in terms of structural and

electronic properties.³⁰

R

OH

Cinacalcet

R= H, Uvangoletin

R= Me Myriggalone

H

Mefloquine

R'

OH

H

N

HN

N

H

O

OH

Cl

N

R

O

N

Investigation of literature revealed that Balaraman and co-workers

synthesized phosphine free NNN Co(II) complexes which catalyzed

direct N-alkylation of anilines with alcohols via hydrogen

autotransfer.^13aKundu and co-workers synthesized phosphine free

NNN Co(II) complexes which catalyzed for dehydrogenative synthesis

of quinolines.^25bTo the best of our knowledge, phosphine free cobalt

complexes derived from NNN donors ligands were never been

utilized for the -alkylation of ketones.

Resveratrol

derivatives

(R)-Propafenone

Amodiaquine

Scheme 1. Selected biologically active molecules contained

alkylated amine, 1,4 diaryl ketone moiety and quinoline motif.

Dehydrogenative activation of alcohols could give rise to innovative

synthetic methodology for the synthesis of different N-heterocycle

via cyclization reaction. Quinoline derivatives are such molecules and

these derivatives could be synthesized by this method. In fact some

related motifs were employed for pharmaceuticals, dyes, pigments,

sensors and polymeric materials.¹⁹Therefore, straight forward

method for the synthesis of N-heterocycles such as pyrimidines,

pyrroles and quinolines from easily available reagents still remains

challenging.²⁰Over the past few years, dehydrogenative cyclization

reaction has become an well-designed protocol which generates

Recently, our group reported organoruthenium complexes

supported on NN-based bidentate ligands, for -alkylation of

ketones with alcohols and synthesis of quinolines.³¹As part of our

interest, we are trying to explore base-metal Co(II) based catalysts

supported by pincer ligands for N-alkylation of amines, -alkylation

of ketones and synthesis of quinolines.

N

CoCl₂.6H₂O

Co

Cl

DCM/CH₃OH

R

R= OCH₂CH₃, Co1

R= NEt₂, Co2

R=NMe₂, Co3

R= OCH₂CH₃, L¹

R= NEt₂, L²

R=NMe₂, L³

Scheme 2. Schematic drawing for synthesis of complexes (Co1-Co3).

2 | J. Name., 2012, 00, 1-3

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This prompted us to study the phosphine free base-metal cobalt band in free ligands (L¹-L³) was observed near 1565–1580 cm^–1

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complexes having pincer ligands. In the present study we have (Shown in Supporting Information, Figures S15-S17). The ESI-MS

designed and synthesized a new family of base-metal cobalt analysis was performed for all the ligands (L¹-L³) in the acetonitrile

complexes Co1, Co2 and Co3 supported by pincer ligands L¹, L²and solution. Ligands L¹-L³provided peaks at m/z = 556.2775, 610.3701

L³(where L¹=2,6-bis(2(4-ethoxybenzylidene)-1-phenylhydrazineyl) and 554.3078 for (L^1-3+H⁺)⁺ions respectively which authenticate the

pyridine, L²=4,4'-((pyridine-2,6-diylbis (2-phenylhydra zin-2-yl-1-ylid formation of Schiff bases. (Shown in Supporting Information, Figures

ene)) bis (methaneyl ylidene)) bis(N,N-diethylaniline) and L³=4,4'- S9-S11)

((pyridine-2,6-diylbis(2-phenyl

hydrazine-2-yl-1-ylidene))

bis Synthesis and characterization of cobalt complexes Co1, Co2 and

methaneylylidene)) bis (N,N-diethyl aniline)) respectively (shown in Co3

Scheme 2). These complexes were characterized by different Cobalt complexes were prepared by the reaction of CoCl₂∙6H₂O and

spectroscopic methods such as UV–Vis., IR and ESI-MS analysis. ligand (L¹-L³) in 1:1 molar ratio in CH₂Cl₂/CH₃OH. (shown in Scheme

Molecular structures of Co1 and Co3 were determined by X-ray 2) After 6 h of stirring, red coloured solid of complexes Co1, Co2 and

Co3 were formed with a good yield (~60%). Coordination of ligand to

the metal centre was characterized by UV-Vis., IR and ESI-MS spectral

studies. The absorption spectra of complexes Co1, Co2 and Co3 were

recorded in dichloromethane solution at room temperature. The

electronic spectral data were shown in (Supplementary Information,

Table S2) and spectra were shown in (Supplementary Information,

Figure S8). The transition band near 330-460 nm for complexes Co1,

Co2 and Co3 was assigned as charge transfer transition.³³In IR,

stretching frequencies for _C=Nin complexes Co1, Co2 and Co3 were

found to be in the range 1560-1605 cm^-1which clearly indicated the

ligation of azomethine nitrogen to metal centre^33a(Shown in SI,

Figures S18-S20). ¹H NMR spectra of all the complexes Co1, Co2 and

Co3 were recorded in CDCl₃solution and were represented in

supporting information (Figures S21-S23). ESI-MS analysis was

performed for all the complexes Co1, Co2 and Co3 in acetonitrile

solution. Complexes Co1, Co2 and Co3 provided peaks at m/z =

649.1600, 703.2652 and 647.2095 for (Co1-Co3-Cl^)⁺ions which

clearly expressed the formation of complexes Co1, Co2 and Co3

(Shown in Supporting Information, Figures S12-S14).

crystallography. We have investigated N-alkylation of amines, -

alkylation of ketones as well as quinoline synthesis by these cobalt

based catalysts. Based on the evidences i.e. characterization of

intermediate species, control experiments and literature studies,

possible reaction pathways will be scrutinized.

Results and discussion

Synthesis and characterization of ligands

Tridentate meridional ligands (L¹-L³) having two imines and one

pyridine donors. Ligands L¹-L³were synthesized by condensation of

2,6-bis(1-phenylhydrazineyl)pyridine³²with 4-ethoxy benzaldehyde,

4-(diethylamino)

benzaldehyde

and

4-(dimethylamino)

benzaldehyde respectively in methanol. Ligands were characterized

by NMR, ESI-MS, UV-Vis. and IR spectroscopic studies and the data

1

were consistent with our previous report.^32aThe H NMR and ¹³C

NMR spectra of ligands (L¹-L³) were observed in CDCl₃and d⁶-DMSO

1

solution (Shown in Figures S1-S6). The H NMR signal of ligands L¹

showed one singlet around ~7.49 ppm for imine proton however,

one quartet around ~4.2 ppm due to the methylene proton of -

OCH₂CH₃proton and one triplet around ~1.4 ppm for -CH₃group. In

L²we have found that one singlet peak at ~7.44 ppm for imine proton

however, one quartet around ~3.3 ppm due to the methylene proton

of -NCH₂CH₃group and one triplet around ~1.1 ppm for -CH₃group.

L³showed one singlet peak around ~7.47 ppm for imine proton

however, one singlet around ~2.9 ppm due to the methyl proton of -

NCH₃group which clearly indicated the formation of ligands. The

electronic spectral data for (L¹-L³) were shown in supplementary

information, (Table S1) and spectra were shown in supplementary

information (Figure S7). In IR, azomethine (-HC=N-) characteristic

Description of crystal structures

Single crystal of cobalt complexes Co1 and Co3 suitable for X-ray

diffraction analysis was obtained by slow evaporation of the cobalt

complexes in CH₂Cl₂/CH₃CN solution. The crystal structure data and

refinement parameters for complexes Co1 and Co3 are depicted in

Supplementary Information (Table S3). Selected bond distances and

bond angles are shown in Supporting Information (Tables S4-S5). The

single-crystal XRD studies of Co1 and Co3 revealed five coordinate

geometry with the pincer ligands (L¹and L³).

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a

Journal Name

c

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DOI: 10.1039/D0DT03748F

b

d

Figure 1. (a, b) ORTEP diagram (30% probability level) of complexes Co1 and Co3. All hydrogen atoms and solvent molecules are omitted

for clarity. (c, d) Distorted trigonal bipyramidal structure around the cobalt atom of complexes Co1 and Co3.

previous reports^33aand the report by Zhang and co-workers.³⁷CoCl

bond length for both complexes Co1 and Co3 are in the range of

2.249 Å2.299 Å. These distances were larger than the values

communicated by our previous report^33aand some reports in the

literature.³⁸However, these values were smaller than the values

reported by Zhang and co-workers.^37aThese bond lengths clearly

In complexes Co1 and Co3, distorted trigonal bipyramidal geometry

were observed with in plane coordination of one pyridine nitrogen

along with two azomethine nitrogen atoms. Two Cl atoms were

observed as axial ligands for both the complexes (Cl2— Co1— Cl1)

angles were 132° for Co1 and 143° for Co3. Geometry of cobalt ion

for Co1 and Co3 were also calculated by trigonality index (

value).^32a,32c value was found to be 0.361 [= (β-α) /60°, where β = indicate that Co(II) high-spin centre was stabilized in presence of

meridional ligands having NNN donors and two Cl atoms.^33a

N1— Co1—N5 =153.49(12) and = Cl2— Co1— Cl1 = 131.83(5)] for

Co1 and for Co3 0.211 [= (β-α) /60°, where β = N1— Co1—N5

=155.3(2) and = Cl2— Co1— Cl1 = 142.63(9)]Thus, the coordination

environment around the metal centre was described as distorted

trigonal bipyramidal for complexes Co1 and Co3.³⁴ORTEP diagram of

cobalt complexes Co1 and Co3 are shown in Figure 1. Co1—N_pybond

lengths for complexes Co1 and Co3 were found to be 1.982(5) Å and

1.988(3) Å respectively. This bond length was smaller than the values

reported in the literature. ^33,35The bond length Co1—N_imfor both the

complexes Co1 and Co3 are in the range of 2.169 Å2.236 Å. These

bond distances were found to be smaller than the values reported by

Batisha and co-workers³⁶and larger than the values reported by our

N-alkylation of anilines with primary alcohols

Our initial investigation focused on the N-alkylation of anilines,

reaction was carried out with aniline (1a), benzyl alcohol (2a) as

substrates and Co1 as catalyst (Shown in Table 1). A series of

reactions were performed to optimize various parameters such as

solvent, temperature, base and time (Shown in SI Figure S24).

Formation of N-benzylaniline 3aa with yield of 82% after 24 h was

observed when the reaction was carried out in presence of Co1 (4

mol%) with aniline (1 mmol) and benzyl alcohol (1 mmol) at 110 C

in toluene solution (Table 1, Entry 5). 54% yield of desired product

3aa was obtained when the reaction was carried out with 3 mol% of

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catalyst Co1 (Table 1, Entry 13). We have performed the reaction in K₃PO₄(Shown in SI, Figure S24). The optimum reaction temperature

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presence of 5 eq. PPh₃and we observed no change in the catalytic was found to be 110 °C (shown in supporting information, Figure

outcome which clearly indicated the homogeneous nature of the S24). Further, the effect of time was also investigated and the

reaction (Table 1, Entry 14). To examine the role of solvent the maximum yield of the formation of product at 24 h (Shown in SI,

reaction was performed in various solvents (Table 1, Entry 6-13) and Figure S24). Control experiments were performed in the absence of

catalyst Co1, only ligand L¹, in-situ generated catalyst system (1:1, L¹

Table 1. Optimization reaction condition for the N-alkylation of

and CoCl₂.6H₂O), and in absence of base KO^tBu. (Table1, Entry 1, 2

anilines.

and 4). In all those control experiments no detectable desired

H

N

Catalyst, Base

NH₂

OH

+

product was obtained. Moreover, commercially available cobalt

sources like CoCl₂.6H₂O and Co(NO₃)₂.6H₂O also examined (Table1,

Entry 3). These observations clearly depicted that the assembled i.e.

coordination complex was important for the catalytic activity. Thus,

the optimized reaction condition was found to be 4 mol% catalyst

loading of catalyst Co1, 0.5 mmol of base KO^tBu in toluene at 110 C

for 24 h.

Solvent, Temp.

Time

2a

1a

3aa

Entry

Cat.

Solvent

Temp

(°C)

Time

(h)

%

Yield

loading

(mol%)

__

1

2

3

Toluene

110

24

0

Ligand L²

4

CoCl₂.6H₂O/

Co(NO₃)₂.6H₂O

L²+CoCl₂. 6H₂O

Trace

4

5

4

Toluene

110

24

Trace

82

We next set out to investigate the reaction scope for N-alkynation

reaction and then, the reaction of benzyl alcohol with structurally

diverse amines were investigated (Table 2) Anilines bearing electron-

donating substituents such as -OCH₃(Table 2, 3ba) on para position,

-OCH₃(Table 2, 3ca) on ortho position, -CH₃(Table 2, 3da and 3db)

on para position with different benzyl alcohols results good (>75%)

to excellent yield (>80%) of N-alkylated products. Electron deficient

substituent bearing i.e. -Cl, on para position smoothly reacted with

benzyl alcohol derivatives to afford products 3ea and 3eb with 70%

to 78% yield. Heterocyclic amine such as 2-amino pyridine could be

transformed into the desired products (Table 2, 3fa) in moderate

yield (>65%) due to the electronic effect. Next, the scope of different

benzyl alcohol derivatives was investigated.

Co1

6

7

Co1

4

3

4

DMSO

DMF

110

24

35

30

8

Benzene

Xylene

EtOH

50

9

52

10

11

12

13

14

Trace

54

THF

ACN

Toluene

^aToluene

78

Reaction Condition: Aniline (1 mmol), Benzyl alcohol (1 mmol),

Catalyst (4 mol%), KO^tBu (0.5 mmol), Toluene 2 ml, Temperature

110 °C for 24 h. ^aIn presence of 5 eq. of PPh₃. Isolated yields.

toluene was observed to be best solvent resulting in yield of 82%.

KO^tBu was found to be the best base for this purpose compared to

other bases like KOH, NaOH, K₂CO₃Na₂CO₃, Et₃N, CH₃COOK and

Table 2. Substrate scope of N-alkylation of anilines

R₂

Catalyst (4 mol%)

Base (0.5 mmol)

NH₂

OH

H

N

Toluene

R₂

+

R₁

1

2

3

R₁, R₂= H , OCH₃, CH₃, Cl

CH₃

OCH₃

OCH3

OCH₃

H

N

H

N

H

N

Co1 79%

Co2 78%

Co3 77%

Co1 82%

Co2 81%

Co3 78%

Co1 85%

Co2 82%

Co3 80%

Co1 83%

Co2 81%

Co3 78%

3ad

3ab

3aa

3ac

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Cl

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H

N

H

N

H

N

Co1 83%

Co2 81%

Co3 77%

3da

Co1 81%

Co2 79%

Co3 77%

3ba

Co1 78%

Co2 74%

Co3 72%

3ae

H₃C

H₃CO

OCH₃

Co1 84%

Co2 82%

Co3 80%

3ca

OCH₃

H

N

H

N

H

N

H

N

Co1 70%

Co2 68%

Co3 65%

3fa

Co1 78%

Co2 76%

Co3 74%

N

Co1 76%

Co2 74%

Co3 70%

Co1 86%

Co2 83%

Co3 80%

Cl

H₃C

3eb

3db

3ea

Reaction Condition: Aniline (1 mmol), Benzyl alcohol (1 mmol), cat. (4 mol%), KO^tBu (0.5 mmol), Toluene 2 ml heated at 110

°C for 24 h. Isolated yields.

Alcohols containing electron-donating 4-OCH₃, 3,4-OCH₃and 4-CH₃temperature, solvent, time and base were optimised and measured

as well as electron deficient 4-Cl reacted with anilines afforded (shown in SI, Figures S49).

desired products (3ab-3ae) with 72% to 85% yield. However, efforts

Table 3. Optimization reaction condition for the -alkylation of

ketones

at the alkylation of electron deficient -NO₂containing amines with

alcohols did not provide the desired products. Acidity, nucleophilicity

O

Catalyst

Base

OH

2a

CH₃

and steric effects of anilines play important roles for N-alkylation

reactions. We have also performed the alkylation of aliphatic amines

with alcohols, however we observed that the catalysts were

ineffective and a trace amount of desired products were formed. The

catalysts were also ineffective for the alkylation of amines with

heterocyclic alcohols.

+

4a

Solvent, Time

5aa

Entry

Cat.

loading

Solvent

Temp

(°C)

Time

(h)

%

Yield

(mol%)

__

1

2

3

Toluene

110

24

0

Ligand L²

CoCl₂.

6H₂O/

Co(NO₃)₂.

6H₂O

L²+CoCl₂.

6H₂O

Co1

2

Trace

We have tried to compare our results, for catalytic activity of Co1-

Co3 for N-alkylation reaction of anilines with benzyl alcohols to

produce the N-alkylated products, with previous literature reports.

The optimum loading of catalysts (Co1-Co3) for catalytic activity (4

mol%) of N-alkylation of anilines is lower than the values reported by

Midya et al. (catalyst loading 5 mol%) by cobalt complexes supported

by ligands having NNN donors.^13aThe data reported by us is

comparable with the data reported by Midya et al. for all the

catalysts (Co1-Co3). Air and moisture insensitivity of our catalysts as

well as phosphorous free complexes are additional advantages.

4

2

Toluene

110

24

Trace

5

6

7

8

9

10

11

12

13

14

1

2

Toluene

DMSO

DMF

Benzene

Xylene

EtOH

THF

ACN

Toluene

^aToluene

110

24

48

42

35

62

64

Trace

91

Co1

87

Reaction Condition: Acetophenone (1 mmol), Benzyl alcohol (1

mmol), catalyst (2 mol%), KO^tBu (0.5 mmol) Toluene 2 ml

Temperature 110 °C for 24 h. ^aIn presence of 5 eq. of PPh₃.Isolated

yields.

-Alkylation of Ketones with Primary Alcohols

Lowering the catalyst loading up to 1 mol% decreased the yield by

58% of desired product 5aa. No retardation of the catalytic cycle was

observed due to the addition of 5 eq. PPh₃to the reaction mixture.

These data clearly expressed the homogenous nature of catalysts.

(Table 1, Entry 14). Toluene were found to the best solvent

compared than other solvents and KO^tBu was found to be the best

base utilized for the reaction (Shown in SI Figures S49). Controlled

In order to demonstrate the potential of catalysts we have examined

-alkylation of ketones. Initially, -alkylation of acetophenone (4a)

and benzyl alcohol (2a) was investigated in presence of catalyst

loading (2 mol%) of Co1 at 110°C in toluene which resulted in the

formation of 1,3-diphenylpropan-1-one 5aa with 91% yield after 24

h (Table 1, Entry 13). To our delight other parameters such as

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experiments were performed in the absence of catalyst Co1, in-situ tolerance (Table 4). The reaction of acetopheno_Vn_iee_{w A}a_rn_ticd_{le O}th_nle_ini_er

DOI: 10.1039/D0DT03748F

generated catalyst system (1:1, L¹and CoCl₂.6H₂O), only ligand L¹and derivatives containing electron rich and electron deficient with

in absence of base KO^tBu. These control experiments resulted in no benzyl alcohol showed high conversion of 82% to 91% of the desired

noticeable formation of desired product 5aa, signifying the products (Table 4, 5aa-5af). Benzyl alcohols having electron-donating

importance of the assembled catalyst i.e. cobalt complex for the substituents (4-OCH₃) reacted with substituted ketones having (4-

catalytic activity. However, commercially available cobalt sources OCH₃, 4-CH₃) groups and halides (4-Br, 4-Cl and 4-F) groups produced

like CoCl₂.6H₂O and Co(NO₃)₂.6H₂O also examined for - alkylation -alkylated product in high to excellent yields of 81% to 95% (Table

reaction which provided no significant formation of desired product 4, 5bb-5bf). However, reaction of ketones having electron-donating

5aa (Table 3, Entry 1-4). Ultimately the optimization reaction (4-OCH₃, 4-CH₃) groups and electron-withdrawing (4-Br, 4-Cl and 4-

performed with 1 mmol of ketone, 1 mmol of alcohol, 2 mol% F) groups with benzyl alcohol having electron rich substituents (3-

catalyst loading of catalyst Co1 and 0.5 mmol base KO^tBu in toluene OCH₃) afforded corresponding substituted 1,3-diphenylpropan-1-

solvent at 110 °C in 24 h for testing of different substrates. Under the one product in high to excellent yields of 81% to 93% (Table 4, 5cb-

established reaction conditions a series of primary alcohols and 5cf).

ketones were investigated for the substrate and functional group

Table 4. Substrate scope of -alkylation of ketones

O

Catalyst (2 mol%)

O

Base (0.05 mmol)

OH

CH₃

+

Toluene

R₂

R₃

R₂

4

2

5

R₃= H , CH₃, OCH₃, F, Cl, Br

R₂= H, OCH₃, CH₃, Cl

O

Co1 92%

Co2 88%

Co3 90%

Co1 91%

Co2 87%

Co3 85%

H₃CO

Co1 89%

Co2 87%

Co3 84%

Co1 90%

Co2 88%

Co3 87%

Br

H₃C

5ab

5aa

5ad

5ac

O

Co1 95%

Co2 92%

Co3 90%

Co1 92%

Co2 89%

Co3 88%

Co1 88%

Co2 85%

Co3 82%

H₃CO

OCH₃

F

OCH₃

Co1 89%

Co2 88%

Co3 83%

Cl

5ba

5bb

5af

5ae

O

Co1 89%

Co2 87%

Co3 82%

Co1 93%

Co2 89%

Co3 90%

Co1 86%

Co2 85%

Co3 81%

Co1 90%

Co2 88%

Co3 84%

Cl

OCH₃

Br

OCH₃

H₃C

OCH₃

F

OCH₃

5be

5bd

5bc

5bf

O

OCH₃

Co1 93%

Co2 90%

Co3 89%

Co1 91%

Co2 89%

Co3 88%

5cc

Co1 89%

Co2 86%

Co3 83%

5cd

Co1 90%

Co2 87%

Co3 86%

5ca

H₃CO

H₃C

Br

5cb

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O

View Article Online

OCH₃

DOI: 10.1039/D0DT03748F

Co1 92%

Co2 90%

Co3 88%

Co1 89%

Co2 88%

Co3 87%

H₃CO

CH₃

Co1 84%

Co2 80%

Co3 82%

Co1 88%

Co2 85%

Co3 81%

CH₃

Cl

F

5db

5da

5ce

5cf

O

Co1 89%

Co2 87%

Co3 84%

Co1 88%

Co2 86%

Co3 84%

Co1 87%

Co2 86%

Co3 84%

Br

CH₃

Co1 85%

Co2 83%

Co3 81%

H₃C

CH₃

Cl

CH₃

F

CH₃

5dd

5dc

5de

5df

O

Cl

O

H₃CO

Co1 86%

Co2 84%

Co3 82%

5dh

Co1 85%

Co2 83%

Co3 81%

Co1 86%

Co2 85%

Co3 83%

Co1 84%

Co2 82%

Co3 80%

5dg

CH₃

Cl

H₃CO

Cl

CH₃

5ea

5eb

O

Co1 84%

Co2 82%

Co3 81%

Co1 80%

Co2 78%

Co3 76%

Co1 78%

Co2 77%

Co3 75%

Co1 77%

Co2 76%

Co3 75%

Br

Cl

H₃C

Cl

F

Cl

5ec

5ed

5ee

5ef

O

Cl

Co1 85%

Co2 83%

Co3 81%

Co1 75%

Co2 73%

Co3 68%

Br

H₃CO

Co1 84%

Co2 82%

Co3 78%

Co1 84%

Co2 82%

Co3 80%

H₃C

5fb

5fd

5fc

5fa

O

OCH₃

Cl

OCH₃

Cl

Co1 98%

Co2 96%

Co3 92%

Co1 97%

Co2 95%

Co3 90%

Co1 73%

Co2 71%

Co3 66%

Co1 71%

Co2 69%

Co3 64%

H₃CO

Cl

F

5gb

5fe

5ga

5ff

O

OCH₃

Co1 87%

Co2 85%

Co3 81%

Co1 94%

Co2 92%

Co3 91%

Co1 89%

Co2 87%

Co3 85%

Co1 90%

Co2 88%

Co3 80%

F

H₃C

Cl

Br

5gf

5gc

5ge

5gd

O

Co1 78%

Co2 75%

Co3 71%

Co1 76%

Co2 72%

Co3 69%

5hb

5ha

Reaction Condition: Acetophenone derivatives (1 mmol), Benzyl alcohol derivatives (1mmol), catalyst (2 mol%), KO^tBu (0.5 mmol)

Toluene 2 ml Temperature 110 °C for 24 h. Isolated yields.

8 | J. Name., 2012, 00, 1-3

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Nevertheless, benzyl alcohols having electron-donating substituents additives, ^tBuOK was found to be the best suitable base for

View Article Online

DOI: 10.1039/D0DT03748F

(4-CH₃) reacted with substituted ketones having (4-OCH₃, 4-CH₃) dehydrogenative cyclization of 2-amino benzyl alcohol. Among

groups and halides (4-Br, 4-Cl and 4-F) groups produced desired different solvent toluene was effective solvent for the conversion of

products 5db-5df in high to excellent yields of 81% to 92%. The the desired product 7aa. On decreasing of catalyst loading (1 mol%)

reaction of benzyl alcohols having electron-withdrawing substituents get suppression of desired product (Table 5, Entry 5). No inhibition

(4-Cl) with substituted ketones having (4-OCH₃, 4-CH₃) groups and of the catalytic reaction was observed due to the addition of 5 eq.

halides (4-Br, 4-Cl and 4-F) groups formed C-alkylated products in PPh₃to the reaction mixture. These data clearly indicated the

good to high yields of 75% to 86% (Table 4, 5eb-5ef). Under similar homogenous nature of catalysts. (Table 1, Entry 14). Control

reaction condition, reaction with ketones having electron rich (4- experiments provided following important information. First,

OCH₃, 4-CH₃) groups and electron deficient (4-Br, 4-Cl and 4-F) reaction attempted with commercially available cobalt sources like

groups and benzyl alcohol having electron-withdrawing substituents CoCl₂.6H₂O and Co(NO₃)₂.6H₂O under optimized conditions gave

(3-Cl) afforded corresponding substituted 1,3-diphenylpropan-1-one poor conversion to the desired product (7aa). (Table 5, Entry 3)

in good to high yields 64% to 85% (Table 4, 5fb-5ff). We also checked Second, no detectable desired product was obtained in presence of

the effect of benzyl alcohols having electron-donating group (3,4- ligand L¹and base ^tBuOK and also in absence of catalyst Co1. Third,

OCH₃) and substituted ketones having halides (4-Br, 4-Cl and 4-F)

Table 5. Optimization reaction condition for the synthesis of

groups and (4-OCH₃, 4-CH₃) groups we ended up with the -alkylated

quinoline

product in high to excellent yields 80% to 98% (Table 4, 5gb-5gf).

O

Catalyst

Base

OH

CH₃

+

Under optimized protocol reaction of acetophenone with

substituted alcohols containing electron rich as well as electron

deficient afforded desired products 5aa, 5ba, 5ca, 5da, 5ea, 5fa and

5ga in high to excellent yield 85% to 97%. Catalytic system also useful

in presence of sterically hindered ketone (2-Cl) gave rise to -

alkylated products in excellent yield 80% to 84% (Table 4, 5dg). The

reaction of electron rich ketone (3-OCH₃) with benzyl alcohols

afforded desired product 5dh in excellent yield of 82% to 86%. We

have also explored the reaction of acetophenone with aliphatic

alcohols gave rise to desired product 5ha and 5hb in good yield of

69% to 78% (shown in SI Figures S169-S172). Significant achievement

has been made for -alkylation of ketones from benzyl alcohols

catalyzed by cobalt-based catalysts via dehydrogenative coupling.

Thus, the present complexes (Co1-Co3) may be effective catalysts for

-alkylation reaction along with phosphorous free reaction

conditions which would be an additional advantage. However,

efforts at the alkylation of ketones with heterocyclic alcohols were

not successful.

Solvent, Temp.

N

4a

NH₂

6a

7aa

Entry

Cat.

Solvent

Temp

Time

(h)

%

Yield

loading

(mol%)

(°C)

__

1

2

3

Toluene

110

24

0

Ligand L¹

2

CoCl₂.

6H₂O/

Co(NO₃)₂.

6H₂O

L¹+CoCl₂.

6H₂O

4

2

Toluene

110

24

Trace

5

6

Co1

1

2

Toluene

DMSO

DMF

110

24

60

45

7

38

8

Benzene

Xylene

EtOH

62

9

64

10

11

12

13

14

Trace

90

THF

ACN

Toluene

86

Reaction Condition: 2-amino benzyl alcohol (1 mmol),

Acetophenone derivatives (1 mmol), catalyst (2 mol%), KO^tBu (0.5

a

mmol) Toluene 2 ml heated at 110 °C for 24 h. In presence of 5

eq. PPh₃. Isolated yields.

Dehydrogenative cyclization of 2-amino benzyl alcohol

we did not find any desired product when we performed the reaction

by in-situ generated catalyst system (1:1, L¹and CoCl₂.6H₂O). (Table

5, Entry 1, 2 and 4). The above control experiments authenticated

the role of ligand as well as complexation of ligand with metal in the

catalytic activity. Gratifyingly, the optimal results with 90% yield of 2-

Further, we have examined dehydrogenative cyclization of 2-amino

benzyl alcohol 6a with acetophenone 4a in presence of Co1 for the

synthesis of 2-phenylquinoline (7aa). Several parameters such as

temperature, solvent, base and time were optimized (Shown in SI,

Figures S138). After investigating the reaction with different base

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Table 6. Substrate scope for synthesis of quinolines

View Article Online

DOI: 10.1039/D0DT03748F

O

Catalyst (2 mol%)

Base (0.5 mmol)

OH

NH₂

CH₃

+

Toluene

N

R₃

6

7

4

R₃= H , OCH₃, CH₃

F, Cl, Br, I

N

Co1 88%

Co2 86%

Co3 84%

Co1 92%

Co2 90%

Co3 88%

Co1 91%

Co2 89%

Co3 87%

Co1 90%

Co2 88%

Co3 84%

Br

OCH₃

CH₃

7ad

7aa

7ab

7ac

N

Co1 85%

Co2 83%

Co3 80%

7af

Co1 86%

Co2 84%

Co3 81%

Co1 89%

Co2 87%

Co3 86%

Co1 88%

Co2 85%

Co3 83%

N

F

Cl

I

7ae

7ag

7ah

N

Co1 89%

Co2 85%

Co3 83%

N

Co1 90%

Co2 89%

Co3 88%

Co1 91%

Co2 90%

Co3 89%

Co1 89%

Co2 87%

Co3 86%

7ai

7ak

7aj

7al

Reaction Condition: 2-aminobenzyl alcohol (1 mmol), acetophenones derivatives (1 mmol), catalyst (2 mol%), KO^tBu

(0.5 mmol) Toluene 2 ml heated at 110 °C for 24 h. Isolated yields.

phenylquinoline (Table 5, Entry 13) were obtained using 2 mol% of the corresponding product 7ak with excellent yield (>88%). However,

catalyst loading for catalyst Co1, 0.5 mmol base in toluene at 110 °C

for 24 h. With the optimal reaction condition established, we next

explored the substrate scope and efficiency of the dehydrogenative

cyclization of 2-amino benzyl alcohol. The reaction of substituted

acetophenone containing electron-donating groups (4-OCH₃, 4-CH₃)

with 2-amino benzyl alcohol afforded corresponding quinoline

derivative in good to excellent yield 87% to 91%. (Table 5 7ab, 7ac)

The transformation of 2-amino benzyl alcohol with electron deficient

acetophenones (4-Br, 4-Cl, 4-F and 4-I) gave the corresponding

quinoline derivatives 7ad, 7ae, 7af and 7ag in good to excellent yield

87% to 91%. We also checked the reaction of hetero acetophenones

(2 and 4 acetyl pyridine) with 2-amino benzyl alcohol formed the

desired product 7ah, 7ai in high to excellent yield 83%-89%. The

catalytic system also effective with sterically hindered ketone and

afforded the corresponding product 7aj in excellent yield (>89%). The

high catalytic activity also observed with alicyclic ketone affording

-tetralone gives the dehydrogenative synthesis of quinoline with 2-

amino benzyl alcohol gave rise to corresponding product (Table 5,

7al) in excellent yield (>86%).

These data obtained from our present study for our catalysts (Co1-

Co3) for dehydrogenative cyclization of 2-amino benzyl alcohol with

ketones were compared with the reports in the literature. The

optimum loading of catalysts (Co1-Co3) for catalytic activity (2 mol%)

for quinoline formation is lower than the values reported by Kundu

and co-workers (catalyst loading 5 mol%) and Balaraman and co-

workers (catalyst loading 2.5 mol%).^25b,18bThus, the catalytic

potential of our catalysts may be placed among the best effective

catalysts known for dehydrogenative cyclization of 2-amino benzyl

alcohol.

Control experiments for N-alkylation of anilines and mechanistic

investigation

10 | J. Name., 2012, 00, 1-3

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View Article Online

DOI: 10.1039/D0DT03748F

Scheme 3. Control experiment for N-alkylation of aniline and reduction of styrene.

To explain the mechanistic pathway, we have performed a series of For mechanistic study we have characterized the possible reaction

control experiments under the optimized reaction conditions intermediates. Initially, we have performed the ESI-MS upon addition

(Scheme 3). The reaction between p-toluidine and benzaldehyde of 4-methoxy benzyl alcohol (5 equivalent) to catalyst Co1 (0.04

mmol) in toluene for 10 min. A peak was generated at m/z= 786.22

which corresponds to the alkoxide species with the molecular

formula [C₄₃H₄₂ClCoN₅O₄-Cl^-+H⁺]⁺(shown in Figure S176). The other

afforded the product 1-phenyl-N-(p-tolyl)methanimine (3c) with

58% yield. However, N-alkylated product was not observed during

the reaction (3c) (Scheme 3A). We next carried out the reaction

between p-toluidine and benzyl alcohol after 8h we observed N- peak which was observed at m/z= 650.17 corresponds to the [CoH]

alkylated product (3c) with 37% yield along with 1-phenyl-N-(p- species having molecular formula [C₃₅H₃₄ClCoN₅O₂-Cl^-]⁺(shown in

Figure S177). These data clearly indicated the formation of alkoxide

species II as well as hydride intermediate III generated during the

catalytic cycle. We have done the ESI-MS after 12 h and found the

peak at m/z= 861.27 which corresponds to the intermediate IV with

the molecular formula [C₄₉H₄₇ClCoN₆O₃-Cl^-]⁺(shown in Figure S177 ).

This data clearly indicated that the reduction of imine in the complex

is not occur during catalytic cycle.^7l,31

tolyl)methanimine (3c) (yield 24%) was deposited in Scheme 3B and

NMR spectral data are shown in SI (Figures S163 and S164). After that

we further utilized 1-phenyl-N-(p-tolyl)methanimine (3c) as reactant

and reacted with benzyl alcohol which gave rise to N-alkylated

product (3c) with 83% yield. To investigate the dehydrogenative

nature of catalytic reaction and to authenticate the H₂evolution

during the reaction, we performed the hydrogenation of styrene in

presence of Pd/C in THF solution. The H₂gas liberated in the first-

round bottom flask during the acceptorless dehydrogenation of 4-

methoxybenzyl alcohol was found to reduce styrene present in the

second-round bottom flask. The reaction mixtures were examined

and formation of ethylbenzene as hydrogenated product was

confirmed.^20d,31The reaction mixture was analyzed by GC-MS

analysis shown in supporting information (Figure S167).

Based on above experimental data and literature reports¹¹we

propose the possible reaction pathway (Scheme S3). Initially,

deprotonated alcohol was bound to the catalyst and generated

intermediate II. Then the dehydrogenative activation of alkoxide

species occurs and produces the benzaldehyde B and intermediate

III was formed. We were successful in characterizing intermediates II

and III. The resulting benzaldehyde B condensed with aniline C

affording imine D. After that imine moiety D inserted into CoH bond

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afforded intermediate IV. Now intermediate IV reacted with alcohol the styrene present in the second-round bottom flask. The reaction

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to produce the N-alkylated product E and catalyst was regenerated.

Control experiments for -alkylation of ketones and mechanistic

investigation

mixtures were examined and confirme^Dd^OI:t¹h⁰e^.103f⁹o^/r^Dm⁰a^Dt^Tio⁰³n⁷⁴⁸o^Ff

ethylbenzene as hydrogenated product. The reaction mixture was

analysed by GC-MS analysis (shown in SI, S165).

On the basis of above experimental findings and previous

reports^18b,31a plausible reaction mechanism was proposed (shown in

Scheme S4). Initially, the reaction of cobalt complex and

deprotonated alcohol in presence of base generates Co-alkoxide

species II (shown in Figure 2). Subsequently, -hydride elimination

of intermediate II gave rise to cobalt-hydride intermediate (shown in

Figure 3) and the aldehyde B. In the next step, cross-aldol reaction of

ketone F and aldehyde afforded ,β unsaturated ketone. Insertion

reaction of α, β-unsaturated ketone G into Co−H bond afforded

intermediate IV produced the -alkylated product H and regenerate

the catalyst.

To shed light on the mechanism of -alkylation reaction we set

similar-type of control experiments under the optimized reaction

conditions (Scheme 4). The reaction between acetophenone and 4-

methoxy benzaldehyde afforded the ,β unsaturated ketone (3ac)

with 59% yield (Scheme 5A). However, in this case we did not

observed -alkylated product (3ac). We had observed that when the

reaction was carried out between acetophenone and 4-methoxy

benzyl alcohol for 10h, a mixture of -alkylated product (3ac) with

45% yield along with ,β unsaturated ketone (3ac) (shown in SI

Scheme 5B, Figures S166 and S165) were obtained. During the

reaction with intermediate ,β unsaturated ketone and 4-methoxy

benzyl alcohol we have observed the formation of -alkylated

product only (3ac) with yield 91%. These reactions clearly dictated

the role of alcohol during catalytic reaction. To authenticate the

dehydrogenative nature of catalytic reaction and to investigate the

H₂evolution during the reaction we performed the hydrogenation of

styrene in presence of Pd/C in THF solution. The H₂gas liberated in

the first-round bottom flask during the acceptorless

dehydrogenation of 4-methoxy benzyl alcohol was found to reduce

Control experiments for dehydrogenative cyclization of 2-amino

benzyl alcohol and mechanistic investigation

To explain the mechanistic study, we tried to identify the possible

reaction intermediates. Initially, we have performed the ESI-MS

generated at m/z= 771.22 which corresponds to the amino-alkoxide

species with the molecular formula [C₄₂H₄₁ClCoN₆O₃-Cl^-]⁺(shown in

Figure S175).

Scheme 4. Control experiments for -alkylation of ketones and reduction of styrene.

12 | J. Name., 2012, 00, 1-3

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The other peak which was observed at m/z: 650.17 corresponds to styrene and formation of ethyl benzene clearly expressed the

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DOI: 10.1039/D0DT03748F

the [CoH] species having molecular formula [C₃₅H₃₄ClCoN₅O₂-Cl^-]⁺

(shown in Figure S176). We performed same procedure mentioned

earlier for dehydrogenative nature of 2-aminobenzyl alcohol (shown

in scheme 4). We came across the formation of ethylbenzene as

hydrogenated product during dehydrogenation of 2-amino benzyl

alcohol (shown in SI, S168)

evolution of hydrogen gas. Studies on modification of the ligands and

other catalytic activities of these useful cobalt-based catalysts are

under progress.

Experimental section

Materials and methods

Analytical grade reagents were used such as phenylhydrazine, (S. D.

Fine, Mumbai, India), 2,6 dichloropyridine (Sigma Aldrich, Steinheim,

Germany), Derivatives of benzaldehydes (Himedia Laboratories Pvt.

Ltd., Mumbai, India), CoCl₂.6H₂O and Co(NO₃)₂.6H₂O (Merck Limited,

Mumbai, India). Solvents used for spectroscopic studies were HPLC

grade and purified by standard procedures before use. All other

chemicals were purchased from commercial suppliers and used as

received without further purification. Infrared (IR) measurements

A probable mechanistic pathway was scrutinized (shown in Scheme

S5) for the dehydrogenative cyclization of 2-amino benzyl alcohol

based on literature reports and our experimental findings.^20bInitially,

the catalyst I was reacted with 2-amino benzyl alcohol in presence of

base and extraction of one molecule of HCl molecule was proposed

giving rise to the formation of intermediate II amino-alkoxide species

(shown in Figure 4). Dehydrogenative activation of alkoxide species

gave rise to species P and intermediate III (shown in Figure 5). The

resulting 2-amino benzaldehyde condense with the ketones G

afforded aldol product Q. Dehydrative cyclization of aldol product Q

occurred and afforded quinoline moiety R. The intermediate III

reacted with another molecule of F regenerated the intermediate II

with the liberation of dihydrogen.

were performed (400–4000 cm^-1) on

a Nicolet FT-IR 6700

spectrometer with samples prepared as KBr pellets. Electronic

spectra were recorded in CH₂Cl₂and CH₃OH with an Evolution 600,

Thermo Scientific UV–Vis. spectrophotometer using cuvettes of 1 cm

path length. C, H, N and O elemental analysis were performed on a

Perkin-Elmer 240B elemental analyzer. A Merck 60 F254 silica gel

plate (0.25 mm thickness) was used for analytical TLC and Merck 60

Conclusions

The following are the major findings and conclusions for the present

investigations.

1

silica gel (100–200 mesh) was used for column chromatography. H

and ¹³C NMR spectra were recorded on Bruker D AVANCE III 500 MHz

(AV 500) (500 MHz), JEOL (400 MHz) spectrometers in the deuterated

solvents. TMS (tetramethylsilane) was used as the internal standard.

Proton coupling patterns are described as singlet (s), doublet (d),

triplet (t), quartet (q), multiplet (m), and broad (br). ESI-MS

experiments were performed on a Brüker micrOTOFTM-Q-II mass

spectrometer.

Cobalt complexes Co1, Co2 and Co3 derived from pincer ligands L¹,

L²and L³respectively were successfully synthesized and

characterized by different spectroscopic methods. Molecular

structures of Co1 and Co3 were determined by X-ray crystallography.

Co1, Co2 and Co3 were successfully utilized for CN bond formation

and synthesis of N-alkylated products. For the substrate scope a total

of 12 entries for N-alkylated products were reported. These catalysts

were found to be effective for CC bond formation and we have

achieved -alkylated compounds. To investigate the functional

group tolerance, a total of 44 -alkylated products were synthesized

and the formation were authenticated. These catalysts were also

found to be efficient in the synthesis of quinoline derivatives. For the

substrate scope a total of 12 cyclized quinoline products were

synthesized and characterized. Control experiments were examined

to get better insight of the reaction pathways. Mechanisms proposed

for the reactions were supported by ESI-MS analysis of Co-alkoxide

and Co-hydride intermediates. The liberation of molecular hydrogen

gas authenticated dehydrogenative nature of catalysts. Reduction of

X-ray Crystallography

Red crystals of complexes Co1 and Co3 were obtained by slow

evaporation of solution from the complexes in CH₂Cl₂/CH₃CN. The X-

ray data collection and processing for complexes were performed on

a Bruker Kappa Apex-II CCD diffractometer by using graphite

monochromated Mo-Kα radiation (λ = 0.71073 Å) at 150 K for

complexes Co1 and Co3 at 293(2) K. Crystal structures were solved

by direct methods. Structure solutions, refinement and data output

were carried out with the SHELXTL program.³⁹All non-hydrogen

atoms were refined anisotropically. Hydrogen atoms were placed in

geometrically calculated positions and refined using a riding model.

Images were created with the DIAMOND program.⁴⁰The “SQUEEZE”

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option in the PLATON program was used to remove a disordered L³was synthesized in similar manner using 4-(dimethylamino)

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DOI: 10.1039/D0DT03748F

solvent molecule from the overall intensity data for complex Co1.⁴¹

Synthesis of ligands

benzaldehyde (298 mg, 2.00 mmol) and 2,6-bis(1-phenylhydrazinyl)

pyridine as described above. Yield 353.92 mg, 62%. Selected IR data:

(KBr, ν/cm^-1): 1575 (_C=N) UV-Vis. [CH₂Cl₂(λ_max/nm (ε/M^-1cm^-1))]:

Synthesis of 2,6-bis(2(4-ethoxybenzylidene)-1-phenylhydrazineyl)

pyridine [L¹]

1

365(63500), 471(3400). H NMR (400 MHz, CDCl₃) δ 7.59 (t, J = 8.1

2,6-bis(1-phenylhydrazinyl) pyridine were synthesized by reported

procedure.³²This was used as a reactant (291 mg, 1.00 mmol) with

4-ethoxybenzaldehyde (300.0 mg, 2.00 mmol) and were dissolved in

5 mL of methanol. The reaction mixture was stirred at room

temperature in open air. Within 40 minutes off-white solid began to

separate out slowly and stirring was continued for another 1 h. Off-

white precipitate was filtered, washed thoroughly with methanol,

diethyl ether and then dried in vacuum. L¹was recrystallized from

dichloromethane. The compound was characterized by UV-Vis., IR,

and NMR spectroscopic studies. Yield: (333 mg, 60%) Selected IR

Hz, 1H), 7.47 (s, 2H), 7.45 (s, 2H), 7.26 – 7.18 (m, 8H), 7.11 (d, J = 8.1

Hz, 2H), 6.95 (d, J = 6.7 Hz, 3H), 6.66 (d, J = 9.0 Hz, 3H), 2.97 (s, 12H).

¹³C NMR (101 MHz, CDCl₃) δ 156.62, 150.74, 139.45, 138.86, 138.11,

129.76, 129.27, 128.77, 127.80, 126.92, 124.39, 112.18, 99.93, 40.49.

Anal. Calc. C₃₅H₃₅N₇: C, 75.92; H, 6.37; N, 17.71 Found C, 75.90; H,

6.34; N, 17.68. HRMS (+ESI) m/z: calcd for [C₃₅H₃₆N₇+H⁺]⁺: 554.3027;

found: = 554.3078 for [L³+H⁺]⁺ion.

Synthesis of complexes

Synthesis of complex Co1

To a 4 mL of dichloromethane solution of ligand L¹(555 mg, 1 mmol)

data: (KBr, ν/cm^-1): 1566 (_C=N) UV-Vis. [CH₂Cl₂(λ_max/nm (ε/M^-1cm^-1)]: a batch of CoCl₂.6H₂O (237 mg, 1 mmol) in 4 mL of methanol was

364(64100), 473(3680). ¹H NMR (400 MHz, CDCl3) δ 7.59 (t, J = 8.0 added. The reaction was stirred for 5 h in open air. Red precipitate

Hz, 1H), 7.49 (s, 2H), 7.47 (s, 2H), 7.27 – 7.08 (m, 7H), 7.20 – 7.16 (m, was filtered and the isolated solid was washed with little amount of

2H), 7.11 (d, J = 8.0 Hz, 2H), 6.95 (d, J = 8.1 Hz, 4H), 6.84 (d, J = 8.7 Hz, methanol. On slow evaporation of CH₂Cl₂/ CH₃CN red coloured

3H), 4.03 (q, J = 7.0 Hz, 4H), 1.41 (t, J = 7.0 Hz, 6H). ¹³C NMR (101 crystals are formed. The compound was characterised by IR, UV-Vis.

MHz, CDCl₃) δ 156.66, 139.60, 138.83, 138.44, 129.73, 129.22, and ESI-MS analysis. Yield: 437.76 mg (64%) Selected IR data: (KBr,

ν/cm^-1): 1562 (_C=N

)

UV-Vis. [CH₂Cl₂, λ_max/nm (ε/M^-1cm^-1)]:

127.99, 126.80, 123.33, 111.53, 99.87, 44.50, 12.70. Anal. Calc.

C₃₅H₃₃N₅O₂: C, 75.65; H, 5.99; N, 12.60 Found C, 75.59; H, 5.95; N,

12.56. HRMS (+ESI) m/z: calcd for [C₃₅H₃₄N₅O₂+H⁺]⁺: 556.2707;

found: 556.2775 for [L¹+H⁺]⁺ion.

334(35020), 390(11960),420(9220). ¹H NMR (500 MHz, CDCl₃) δ 7.52

(t, J = 8.0 Hz, 1H), 7.42 (s, 1H), 7.40 (s, 1H), 7.21 – 7.15 (m, 6H), 7.09

(s, 1H), 7.02 (d, J = 8.0 Hz, 2H), 6.87 (d, J = 6.8 Hz, 4H), 6.77 (d, J = 8.5

Hz, 4H), 3.98 (q, J = 1 6.9 Hz, 4H), 1.35 (t, J = 6.9 Hz, 6H). Anal. Calc.

For C₃₅H₃₃Cl₂CoN₅O₂; C, 61.32; H, 4.85; N, 10.22. Found: C, 61.16; H,

4.92; N, 10.31. HRMS (+ESI) m/z: calcd for [C₃₅H₃₃CoClN₅O₂Cl^-]⁺:

649.1655; found: = 649.1600 for (Co1-Cl^-)⁺ion.

Synthesis of 4,4'-((pyridine-2,6-diylbis(2-phenylhydrazin-2-yl-1-

ylidene))bis(methaneyl ylidene)) bis(N,N-diethylaniline) [L²]

L²was synthesized in similar manner using 4-(diethylamino)

benzaldehyde (234 mg, 2.00 mmol) and 2,6-bis(1-phenylhydrazinyl)

pyridine as described above. Yield: 377.58 mg, 62%. Selected IR data:

(KBr, ν/cm^-1): 1565 (_C=N) UV-Vis. [CH₂Cl₂(λ_max/nm (ε/M^-1cm^-1))]:

Synthesis of complex Co2

To a 4 mL of dichloromethane solution of ligand L²(609 mg, 1 mmol)

a batch of CoCl₂.6H₂O (237 mg, 1 mmol) in 4 mL of methanol was

added. The reaction was stirred for 5 h in open air. Red precipitate

was filtered which was washed with little amount of methanol. The

compound was characterised by IR, UV-Vis.and ESI-MS analysis.

1

326(35040), 366(55430). H NMR (400 MHz, CDCl₃) δ 7.59 (t, J = 8.0

Hz, 1H), 7.44 (s, 2H), 7.42 (s, 2H), 7.25 – 7.15 (m, 8H), 7.11 (d, J = 8.0

Hz, 2H), 6.94 (d, J = 8.1 Hz, 3H), 6.62 (d, J = 8.9 Hz, 4H), 3.37 (q, J = 7.0

Hz, 8H), 1.16 (t, J = 7.0 Hz, 12H). ¹³C NMR (101 MHz, CDCl₃) δ 156.66,

148.11, 139.60, 138.83, 138.44, 129.73, 129.22, 127.99, 126.80,

123.33, 111.53, 99.87, 44.50, 12.70. Anal. Calc. C₃₉H₄₃N₇: C, 76.81; H,

7.11; N, 16.08 Found C, 76.83; H, 7.08; N, 16.10. HRMS (+ESI) m/z:

calcd for [C₃₉H₄₄N₇+H⁺]⁺: 610.3653; found: 610.3701 for [L²+H⁺]⁺ion.

Synthesis of 4,4'-((pyridine-2,6-diylbis(2-phenylhydrazin-2-yl-1-

ylidene))bis (methaneyl ylidene)) bis(N,N-dimethylaniline) [L³]

Yield: 457.56 mg (62%) Selected IR data: (KBr, ν/cm^-1): 1562 (_C=N

UV-Vis. [CH₂Cl₂, λ_max/nm 356(56290),

(ε/M^-1cm^-1)]:

)

1

418(17060),454(10790). H NMR (500 MHz, CDCl₃) δ 7.85 (t, J = 4.5

Hz, 1H), 7.73 (s, 1H), 7.71 (s, H), 7.51 – 7.47 (m, 3H), 7.38 (d, J = 15.4

Hz, 4H), 7.07 (d, J = 4.9 Hz, 4H), 7.02 – 6.98 (m, 2H), 6.92 – 6.85 (m,

3H), 6.69 (d, J = 8.6 Hz, 4H), 3.46 (q, J = , 6.8 Hz, 8H), 1.23 (t, J = 7.1

14 | J. Name., 2012, 00, 1-3

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Hz, 12H). Anal. Calc. For C₃₉H₄₃Cl₂CoN₇; C, 63.33; H, 5.86; N, 13.26. N-(4-methoxybenzyl)aniline (3ab)⁴²: Light yellow liquid, Yield: Co1

View Article Online

DOI: 10.1039/D0DT03748F

Found: C, 63.30; H, 5.91; N, 13.18. HRMS (+ESI) m/z: calcd for (181.05 mg, 85%), Co2 (174.66 mg, 82%), Co3 (170.4 mg, 80%). ¹H

[C₃₉H₄₃CoClN₇Cl^-]⁺: 703.2600; found: = 703.2652 for (Co2-Cl^-)⁺ion.

NMR (400 MHz, CDCl₃) δ 7.35 (d, J = 8.7 Hz, 2H), 7.25 – 7.21 (m, 2H),

6.94 (d, J = 8.7 Hz, 2H), 6.78 (t, J = 7.3 Hz, 2H), 6.69 (d, J = 7.6 Hz, 2H),

4.30 (s, 2H), 4.00 (s, 1H), 3.85 (s, 3H). ¹³C NMR (126 MHz, CDCl₃) δ

158.94, 148.32, 131.52, 129.33, 128.88, 117.56, 114.10, 112.93,

55.35, 47.84.

Synthesis of complex Co3

To a 4 mL of dichloromethane solution of ligand L³(553 mg, 1 mmol)

a batch of CoCl₂.6H₂O (237 mg, 1 mmol) in 4 mL of methanol was

added. The reaction was stirred for 5 h in open air. Red precipitate

was filtered which was washed with little amount of methanol. On

slow evaporation of CH₂Cl₂/ CH₃CN red coloured crystals are formed.

The compound was characterised by IR, UV-Vis. and ESI-MS analysis.

1,2-dimethoxy-4-phenethylbenzene (3ac)⁴³: Pale yellow liquid,

Yield: Co1 (200.86 mg, 83%), Co2 (196.02 mg, 81%), Co3 (188.76 mg,

78%) ¹H NMR (400 MHz, CDCl₃) δ 7.28 (d, J = 10.6, 5.5 Hz, 1H), 7.02 –

6.95 (m, 2H), 6.88 – 6.79 (m, 2H), 6.70 (t, J = 7.8 Hz, 1H), 6.61 (d, J =

8.0 Hz, 1H), 4.66 (s, 1H), 4.35 (s, 2H), 3.88 (s, 3H), 3.82 (s, 3H). ¹³C

NMR (101 MHz, CDCl₃) δ 159.96, 146.87, 141.43, 138.21, 129.67,

121.36, 119.86, 116.75, 113.11, 112.64, 110.20, 109.46, 55.50, 55.30,

48.16.

Yield: 443.30 mg (65%) Selected IR data: (KBr, ν/cm^-1): 1558 (_C=N

)

UV-Vis. [CH₂Cl₂, λ_max/nm (ε/M^-1cm^-1)]: 369(80400), 419(27440),

1

456(17240). H NMR (500 MHz, CDCl₃) δ 7.53 (t, J = 7.0 Hz, 1H), 7.45

(s, 1H), 7.43 (s, 1H), 7.34 (d, J = 8.4 Hz, 2H), 7.17 – 7.14 (m, 4H), 7.13

– 7.08 (m, 2H), 7.01 (d, J = 7.9 Hz, 3H), 6.81 (d, J = 7.4 Hz, 4H), 6.66

(d, J = 8.5 Hz, 1H), 6.60 – 6.55 (m, 3H), 2.91 (s, 12H). Anal. Calc. For

C₃₅H₃₅Cl₂CoN₇; C, 61.50; H, 5.16; N, 14.34. Found: C, 61.34; H, 5.22;

N, 14.43. HRMS (+ESI) m/z: calcd for [C₃₅H₃₅CoClN₇Cl^-]⁺: 647.1974;

found: = 647.2095 for (Co3-Cl^-)⁺ion.

N-(4-methylbenzyl)aniline (3ad)⁴²: Light yellow liquid, Yield: Co1

(155.63 mg, 79%), Co2 (153.66 mg, 78%), Co3 (151.69 mg, 77%). ¹H

NMR (400 MHz, CDCl₃) δ 7.38-7.35 (m, 2H), 7.36 – 7.33 (m, 2H), 7.29

(d, J = 6.9 Hz, 1H), 7.01 (d, J = 8.5 Hz, 2H), 6.58 (d, J = 8.4 Hz, 2H), 4.33

(s, 2H), 3.92 (s, 1H), 2.26 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 146.03,

139.76, 129.84, 128.70, 127.59, 127.25, 126.85, 113.09, 48.74, 20.49.

N-(4-chlorobenzyl)aniline (3ae)⁴²: Colourless liquid, Yield: Co1

(169.26 mg, 78%), Co2 (160.08 mg, 74%), Co3 (156.24 mg, 72%). ¹H

NMR (400 MHz, CDCl₃) δ 7.41 (d, J = 7.4 Hz, 2H), 7.38 (d, J = 7.0 Hz,

1H), 7.32 (d, J = 5.2 Hz, 1H), 7.23 (d, J = 8.1 Hz, 3H), 6.76 (d, J = 7.3 Hz,

1H), 6.67 (d, J = 6.5 Hz, 2H), 4.36 (s, 2H), 4.04 (s, 1H). ¹³C NMR (101

MHz, CDCl₃) δ 156.28, 146.86, 138.61, 138.24, 137.87, 134.54,

133.96, 132.83, 131.02, 130.32, 129.50, 128.65, 47.42.

General procedure for N-alkylation of anilines

The catalytic reaction was performed by following procedure. To a

10mL, clean, oven-dried, screw cap reaction tube containing

complexes (0.04 mmol), benzyl alcohols (1 mmol), anilines (1 mmol),

KO^tBu (0.5 mmol), and toluene (2 mL) were reacted in argon

atmosphere. The reaction mixture was stirred at 110 °C for 24 h.

Then, the reaction mixture was diluted with water (5 mL) and

extracted with ethyl acetate (3 × 5 mL) and filtered off through

Whatman 41 filter paper. The resultant organic layer was dried over

anhydrous sodium sulphate and the solvent was evaporated under

reduced pressure. The crude mixture was purified by silica gel

column chromatography (100–200 mesh size) using hexane/ethyl

acetate as the eluting system. The isolated products were

N-(4-chlorobenzyl)-4-methoxyaniline (3ba)⁴⁴: White solid, Yield: Co1

(200.07 mg, 81%), Co2 (195.13 mg, 79%), Co3 (190.19 mg, 77%). ¹H

NMR (400 MHz, CDCl₃) δ 7.31 (m, 4H), 7.28 (d, J = 8.3 Hz, 1H), 6.84 –

6.78 (m, 2H), 6.71 – 6.66 (m, 1H), 6.53 (d, J = 7.7 Hz, 1H), 4.65 (s, 1H),

4.33 (s, 2H), 3.86 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 146.87, 138.25,

137.88, 132.84, 128.78, 121.33, 116.97, 110.20, 109.54, 55.51, 47.43.

N-benzyl-2-methoxyaniline (3ca)⁴⁵: Brownish oil, Yield: Co1 (178.92

mg, 84%), Co2 (174.66 mg, 82%), Co3 (170.4 mg, 80%). ¹H NMR (500

MHz, CDCl₃) δ 7.38 (d, J = 6.9 Hz, 3H), 7.35 (d, J = 7.3 Hz, 3H), 7.28 (d,

J = 6.7 Hz, 1H), 6.81 (d, J = 6.6 Hz, 2H), 6.68 (s, 1H), 6.61 (s, 1H), 4.63

(s, 1H), 4.36 (s, 1H), 3.85 (s, 3H). ¹³C NMR (126 MHz, CDCl₃) δ 146.79,

139.59, 138.15, 128.58, 127.53, 127.20, 121.28, 117.42, 116.63,

111.51, 110.08, 109.40, 55.42, 48.05.

1

authenticated by H and ¹³C NMR spectra displayed in Supporting

Information (Figures S25-S48).

N-benzylaniline (3aa)^13a: Colourless oil, Yield: Co1 (150.06 mg, 82%),

Co2 (148.23 mg, 81%), Co3 (142.74 mg, 78%).¹H NMR (400 MHz,

CDCl₃) δ 744-7.41 (m, 4H), 7.34 (t, J = 6.7 Hz, 1H), 7.23 (d, J = 7.7 Hz,

2H), 6.79 (t, J = 7.3 Hz, 1H), 6.69 (d, J = 7.6 Hz, 2H), 4.37 (s, 2H), 4.06

(s, 1H). ¹³C NMR (101 MHz, CDCl₃) δ 148.32, 139.62, 129.44, 128.80,

127.67, 127.39, 117.72, 113.01, 48.45.

J. Name., 2013, 00, 1-3 | 15

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Journal Name

N-benzyl-4-methylaniline (3da)¹¹: Colourless oil, Yield: Co1 (163.51 reacted in inert condition. The reaction mixture was heated at 110 °C

View Article Online

DOI: 10.1039/D0DT03748F

mg, 83%), Co2 (159.57 mg, 81%), Co3 (151.69 mg, 77%).¹H NMR (400 with constant stirring in a preheated oil bath for 24 h. The resulting

MHz, CDCl₃) δ 7.40 – 7.34 (m, 4H), 7.28 (s, 1H), 7.01 (d, J = 8.5 Hz, solution was then filtered off through Whatman 41 filter paper. The

2H), 6.58 (d, J = 8.4 Hz, 2H), 4.33 (s, 2H), 3.92 (s, 1H), 2.26 (s, 3H). ¹³

NMR (101 MHz, CDCl₃) δ 146.03, 139.76, 129.84, 128.70, 127.59, was extracted by a solvent extraction technique using a water/ethyl

127.25, 126.85, 113.09, 48.74, 29.81, 20.49. acetate solvent mixture. The organic layer was collected and

C

filtrate was dried under reduced pressure, and the organic product

N-(4-methoxybenzyl)-4-methylaniline (3db)⁴⁶: White solid, Yield: removed through rotary evaporator. The residue was then purified

Co1 (195.22 mg, 86%), Co2 (188.41 mg, 83%), Co3 (181.6 mg, 80%).¹H by 100-200 mesh silica-gel column chromatography to afford the

1

NMR (400 MHz, CDCl₃) δ 7.86 (d, J = 8.7 Hz, 1H), 7.32 (s, 2H), 7.18 (d, pure product. The isolated products were authenticated by H and

J = 8.3 Hz, 2H), 7.01 (d, J = 8.3 Hz, 3H), 6.90 (d, J = 8.6 Hz, 2H), 6.58 13C NMR spectra displayed in Supporting Information (Figure S50-

(d, J = 8.4 Hz, 2H), 4.25 (s, 2H), 3.89 (s, 1H), 3.82 (s, 3H), 2.26 (s, 3H). S137) and (Figure S169-S172) .

¹³C NMR (101 MHz, CDCl₃) δ 146.03, 139.76, 129.84, 128.70, 127.59, 1,3-diphenylpropan-1-one (5aa)⁴⁹: White solid, Yield: Co1 (191.11

127.25, 126.85, 113.09, 48.74, 29.81, 20.49.

mg, 91%), Co2 (182.7 mg, 87%), Co3 (178.50 mg, 85%). ¹H NMR (400

N-benzyl-4-chloroaniline (3ea)⁴⁴: Colourless oil, Yield: Co1 (164.92 MHz, CDCl₃) δ 7.97 (d, J = 8.0 Hz, 2H), 7.55 (d, J = 7.4 Hz, 1H), 7.45 (d,

mg, 76%), Co2 (160.58 mg, 74%), Co3 (151.90 mg, 70%).¹H NMR (400 J = 7.3 Hz, 2H), 7.28 (d, J = 8.2 Hz, 3H), 7.21 (s, 1H), 7.14 (s, 1H), 3.34

MHz, CDCl₃) δ 7.29 (d, J = 8.4 Hz, 2H), 7.13 (d, J = 8.3 Hz, 2H), 6.91 (d, (t, J = 7.7 Hz, 2H), 3.06 (t, J = 8.0 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ

J = 8.2 Hz, 2H), 6.56 (d, J = 8.7 Hz, 2H), 4.23 (s, 1H), 3.82 (s, 2H). ¹³

C

199.33, 141.38, 139.59, 136.94, 133.18, 129.69, 128.14, 126.24,

NMR (101 MHz, CDCl₃) δ 159.05, 146.86, 132.13, 131.03, 128.99, 40.54, 30.21.

128.77. 127.4, 122.04, 114.12, 55.41, 47.90.

1-(4-methoxyphenyl)-3-phenylpropan-1-one (5ab)⁴⁹: Yellow oil,

4-chloro-N-(4-methoxybenzyl)aniline (3eb)⁴⁷: White solid, Yield: Yield: Co1 (208.84 mg, 92%), Co2 (204.3 mg, 90%), Co3 (199.76 mg,

Co1 (192.66 mg, 78%), Co2 (187.72 mg, 76%), Co3 (182.78 mg, 88%).¹H NMR (400 MHz, CDCl₃) δ 7.95 (d, J = 8.9 Hz, 2H), 7.28 (m,

74%).¹H NMR (400 MHz, CDCl₃) δ 7.28 (d, J = 8.4 Hz, 2H), 7.12 (d, J = 4H), 7.21 (t, J = 7.0 Hz, 1H), 6.93 (d, J = 8.9 Hz, 3H), 3.86 (s, 3H), 3.25

8.7 Hz, 2H), 6.90 (d, J = 8.2 Hz, 2H), 6.55 (d, J = 8.7 Hz, 2H), 4.22 (s, (t, J = 8.2 Hz, 2H), 3.06 (t, J = 7.3 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ

2H), 4.02 (s, 1H), 3.81 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 159.05, 197.91, 163.55, 141.57, 130.40, 130.06, 128.57, 126.18, 113.83,

146.86, 132.13, 131.03, 128.99 127.47, 122.04, 114.12, 55.41, 47.90. 55.55, 40.20, 30.43.

N-(4-methoxybenzyl)pyridin-2-amine (3fa)⁴⁸: Colourless oil, Yield: 3-phenyl-1-(p-tolyl)propan-1-one (5ac)⁴⁹: Yellow oil, Yield: Co1

Co1 (149.82 mg, 70%), Co2 (145.52 mg, 68%), Co3 (139.10 mg, 65%). (201.6 mg, 90%), Co2 (197.12 mg, 88%), Co3 (194.88 mg, 87%).¹H

¹H NMR (400 MHz, CDCl₃) δ 8.09 (d, J = 6.2 Hz, 1H), 7.42 – 7.37 (m, NMR (500 MHz, CDCl₃) δ 7.88 (d, J = 8.2 Hz, 2H), 7.30 (d, J = 7.2 Hz,

2H), 7.27 (d, J = 6.9 Hz, 2H), 6.87 (d, J = 8.6 Hz, 2H), 6.58 (d, J = 7.2Hz, 2H), 7.27 (d, J = 2.4 Hz, 2H), 7.25 (s, 1H), 7.22 (t, J = 7.1 Hz, 2H), 3.30

1H), 6.36 (d, J = 7.4 Hz, 1H), 4.86 (s, 1H), 4.41 (s, 2H), 3.79 (s, 3H). ¹³

C

(t, J = 7.9 Hz, 2H), 3.09(t, J = 8.0 Hz, 2H ), 2.42 (s, 3H). ¹³C NMR (101

NMR (101 MHz, CDCl₃) δ 158.94, 158.70, 148.22, 137.59, 131.19, MHz, CDCl₃) δ 198.99, 143.92, 141.49, 134.48, 129.37, 128.56,

128.78, 114.12, 113.17, 106.88, 55.37, 45.91.

128.26, 126.18, 40.43, 30.31, 21.72.

1-(4-bromophenyl)-3-phenylpropan-1-one (5ad)^18b: Off-white solid,

Yield: Co1 (256.32 mg, 89%), Co2 (250.56 mg, 87%), Co3 (241.92 mg,

84%). ¹H NMR (400 MHz, CDCl₃) δ 7.82 (d, J = 8.6 Hz, 2H), 7.60 (d, J =

8.6 Hz, 2H), 7.34 – 7.29 (m, 2H), 7.28 – 7.22 (m, 3H), 3.27 (t, J = 7.7

Hz, 2H), 3.10 (t, J = 8.0 Hz, 2H).¹³C NMR (101 MHz, CDCl₃) δ 198.24,

141.14 , 135.65, 132.01, 129.67, 128.85, 126.33, 40.49, 30.13.

1-(4-chlorophenyl)-3-phenylpropan-1-one (5ae)⁴⁹: Yellow oil, Yield:

Co1 (217.16 mg, 89%), Co2 (214.72 mg, 88%), Co3 (202.52 mg,

83%).¹H NMR (500 MHz, CDCl₃) δ 7.93 (d, J = 7.7 Hz, 2H), 7.47 (d, J =

7.7 Hz, 2H), 7.30 (d, J = 7.4 Hz, 2H), 7.22 (d, J = 7.8 Hz, 2H), 3.29 (t, J

(E)-1-phenyl-N-(p-tolyl)methanimine (3c)^{13d 1}H NMR (400 MHz,

:

CDCl₃) δ 8.43 (s, 1H), 7.83 (d, J = 8.5 Hz, 2H), 7.44 (d, J = 8.5 Hz, 2H),

7.30 – 7.18 (m, 3H), 7.16 – 7.11 (m, 2H), 2.38 (s, 3H).

General procedure for -alkylation of ketones with primary

alcohols

The catalytic reactions were performed following

a general

procedure. To a 10mL, clean, oven-dried, screw cap reaction tube

containing 1 mmol of alcohols, 1 mmol ketones in dry toluene (2 mL),

solvent was mixed with 2 mol % catalyst, 0.5 mmol KO^tBu were

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ARTICLE

= 7.5 Hz, 2H), 3.08 (t, J = 7.4 Hz, 2H). ¹³C NMR (126 MHz, CDCl₃) δ 3.79 (s, 3H), 3.26 (t, J = 7.7 Hz, 2H ), 2.98 (t, J = 7.6 Hz, 2H). ¹³

197.60, 139.58, 135.05, 131.98, 130.44, 129.82, 129.43, 128.98, (101 MHz, CDCl₃) δ 198.24, 158.12, 139.54, ^D1^O35^I:.¹2⁰7^.,¹⁰1³3⁹3^/.^D1⁰5^D, ^T1⁰2³9⁷.⁴4⁸9^F,

128.65, 115.00, 40.12, 29.29. 128.99, 114.05, 55.35, 40.77, 29.28.

1-(4-fluorophenyl)-3-phenylpropan-1-one (5af)⁴⁹: Off-white solid, 1-(4-fluorophenyl)-3-(4-methoxyphenyl)propan-1-one

_{View Artic}C_{le O}N_nM_linR_e

(5bf)³¹:

Yield: Co1 (200.64 mg, 88%), Co2 (193.80 mg, 85%), Co3 (186.96 mg, White solid, Yield: Co1 (221.88 mg, 86%), Co2 (219.39 mg, 85%), Co3

82%). ¹H NMR (500 MHz, CDCl₃) δ 7.99 (m, 2H), 7.32 – 7.29 (m, 2H), (208.98 mg, 81%). ¹H NMR (400 MHz, CDCl₃) δ 7.98 (d, J = 8.9 Hz, 2H),

7.26 (s, 1H), 7.25 – 7.21 (m, 2H), 7.12 (t, J = 8.6 Hz, 2H), 3.28 (t, J = 7.7 7.14 (d, J = 7.2 Hz, 2H), 7.10 (d, J = 8.7 Hz, 2H), 6.84 (d, J = 8.7 Hz, 2H),

Hz, 2H), 3.07 (t, J = 7.7 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 197.70, 3.79 (s, 3H), 3.24 (t, J = 7.7 Hz, 2H), 3.01 (t, J = 7.6 Hz, 2H). ¹³C NMR

167.08, 164.54, 141.22, 133.36, 130.74, 128.57, 126.28, 115.89, (101 MHz, CDCl₃) δ 197.86, 167.05, 164.52, 158.12, 133.56, 130.74,

115.67, 40.46, 30.18.

129.43, 115.76, 115.44, 114.04, 55.35, 40.70, 29.34.

3-(4-methoxyphenyl)-1-phenylpropan-1-one (5ba)⁴⁹: Yellow oil, 3-(3-methoxyphenyl)-1-phenylpropan-1-one (5ca)³¹: Yellow oil,

Yield: Co1 (220.80 mg, 92%), Co2 (213.60 mg, 89%), Co3 (211.20 mg, Yield: Co1 (216.0 mg, 90%), Co2 (208.8 mg, 87%), Co3 (206.4 mg,

88%).¹H NMR (400 MHz, CDCl₃) δ 7.97 (d, J = 7.1 Hz, 2H), 7.56 (t, J = 86%). ¹H NMR (400 MHz, CDCl₃) δ 7.97 (d, J = 7.1 Hz, 2H), 7.56 (t, J =

7.4 Hz, 1H), 7.46 (t, J = 7.6 Hz, 2H), 7.18 (d, J = 8.6 Hz, 2H), 6.86 (d, J 7.4 Hz, 1H), 7.46 (t, J = 7.6 Hz, 2H), 7.22 (d, J = 7.9 Hz, 1H), 6.86 (d, J

= 8.7 Hz, 2H), 3.79 (s, 3H), 3.27 (t, J = 8.0 Hz, 2H), 3.05 (t, J = 7.3 Hz, = 7.6 Hz, 1H), 6.82 (s, 1H), 6.77 (d, J = 8.2 Hz, 1H), 3.80 (s, 3H), 3.31

2H). ¹³C NMR (101 MHz, CDCl₃) δ 199.47, 158.10, 137.00, 133.41, (t, J= 7.5, 2H), 3.05 (t, J = 7.4 Hz, 3H). ¹³C NMR (101 MHz, CDCl₃) δ

133.13, 129.46, 128.70, 128.14, 114.04, 55.36, 40.79, 29.37.

199.29, 159.84, 143.04, 136.93, 133.19, 129.63, 128.72, 128.15,

1,3-bis(4-methoxyphenyl)propan-1-one (5bb)³¹: Yellow solid, Yield: 120.88, 114.34, 111.51, 55.25, 40.46, 30.26.

Co1 (256.50 mg, 95%), Co2 (248.40 mg, 92%), Co3 (243.00 mg, 90%). 3-(3-methoxyphenyl)-1-(4-methoxyphenyl)propan-1-one (5cb)³¹:

¹H NMR (500 MHz, CDCl₃) δ 7.94 (d, J = 7.9 Hz, 2H), 7.17 (d, J = 7.7 Hz, Yellow oil, Yield: Co1 (251.1 mg, 93%), Co2 (243.0 mg, 90%), Co3

2H), 6.92 (d, J = 7.9 Hz, 2H), 6.84 (d, J = 7.6 Hz, 2H), 3.85 (s, 3H), 3.78 (240.3 mg, 89%).¹H NMR (400 MHz, CDCl₃) δ 7.94 (d, J = 8.9 Hz, 2H),

(s, 3H), 3.21 (t, J = 7.6 Hz, 2H), 3.00 (t, J = 7.5 Hz, 2H). ¹³C NMR (126 7.22 (t, J = 7.9 Hz, 1H), 6.92 (d, J = 8.9 Hz, 2H), 6.85 (d, J = 7.6 Hz, 1H),

MHz, CDCl₃) δ 197.93, 163.46, 158.02, 133.51, 130.30, 129.33, 6.81 (s, 1H), 6.76 (d, J = 8.2 Hz, 1H), 3.86 (s, 3H), 3.80 (s, 3H), 3.27 (t,

113.95, 113.72, 55.39, 55.22.

J = 7.6 Hz, 2H), 3.06(t, J = 7.4 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ

3-(4-methoxyphenyl)-1-(p-tolyl)propan-1-one (5bc)³¹: Yellow oil, 197.92, 163.54, 159.79, 143.20, 130.70, 130.41, 129.99, 129.59,

Yield: Co1 (236.22 mg, 93%), Co2 (228.60 mg, 90%), Co3 (226.06 mg, 120.87, 114.30, 113.81, 111.44, 55.56, 55.25, 40.13, 30.45.

89%). ¹H NMR (500 MHz, CDCl₃) δ 7.91 (d, J = 8.2 Hz, 2H), 7.29 (d, J = 3-(3-methoxyphenyl)-1-(p-tolyl)propan-1-one (5cc)³¹: Yellow oil,

8.0 Hz, 2H), 7.22 (d, J = 8.6 Hz, 2H), 6.89 (d, J = 8.6 Hz, 2H), 3.83 (s, Yield: Co1 (231.14 mg, 91%), Co2 (226.06 mg, 89%), Co3 (223.52 mg,

3H), 3.30 (t, J = 7.8 Hz, 2H ), 3.06 (t, J = 7.7 Hz, 2H), 2.45 (s, 3H). ¹³

NMR (101 MHz, CDCl₃) δ 199.14, 158.07, 143.89, 134.53, 133.52, 7.7 Hz, 3H), 7.22 (d, J = 7.9 Hz, 1H), 6.86 (d, J = 7.6 Hz, 1H), 6.82 (s,

129.42, 128.28, 114.02, 55.39, 40.69, 29.47, 21.75. 1H), 6.77 (d, J = 8.2 Hz, 1H), 3.80 (s, 3H), 3.26 (t, J = 7.1 Hz, 2H), 3.04

C

88%).¹H NMR (400 MHz, CDCl₃) δ 7.87 (d, J = 8.2 Hz, 2H), 7.26 (d, J =

1-(4-bromophenyl)-3-(4-methoxyphenyl)propan-1-one (5bd)³¹: Off- (t, J = 7.4 Hz, 2H), 2.41 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 198.94,

white solid, Yield: Co1 (286.20 mg, 90%), Co2 (279.84 mg, 88%), Co3 159.84, 143.92, 143.14, 134.49, 129.44, 128.26, 120.81, 114.25,

(267.12 mg, 84%). ¹H NMR (400 MHz, CDCl₃) δ 7.80 (d, J = 8.6 Hz, 2H), 111.46, 55.29, 40.33, 30.35, 21.75.

7.58 (d, J = 8.6 Hz, 2H), 7.16 (d, J = 8.6 Hz, 2H), 6.86 – 6.82 (m, 2H), 1-(4-bromophenyl)-3-(3-methoxyphenyl)propan-1-one (5cd)³¹: Off-

3.78 (s, 3H), 3.22 (t, J = 7.6 Hz, 2H), 3.00 (t, J = 7.6 Hz, 2H). ¹³C NMR white solid, Yield: Co1 (283.02 mg, 89%), Co2 (273.48 mg, 86%), Co3

(126 MHz, CDCl₃) δ 198.41, 158.19, 135.74, 133.17, 132.01, 129.69, (263.94 mg, 83%). ¹H NMR (500 MHz, CDCl₃) δ 7.81 (d, J = 8.6 Hz, 2H),

129.46, 128.28, 114.10, 55.38, 40.75, 29.31.

7.58 (d, J = 8.6 Hz, 2H), 7.22 (t, J = 7.9 Hz, 1H), 6.84 (d, J = 7.5 Hz, 1H),

1-(4-chlorophenyl)-3-(4-methoxyphenyl)propan-1-one

(5be)³¹: 6.80 (s, 1H), 6.76 (d, J = 8.1 Hz, 1H), 3.80 (s, 3H), 3.27 (t, J = 7.6 Hz,

White solid, Yield: Co1 (243.86 mg, 89%), Co2 (238.38 mg, 87%), Co3 2H), 3.04 (t, J = 7.7 Hz, 2H). ¹³C NMR (126 MHz, CDCl₃) δ 198.10,

(224.68 mg, 82%). ¹H NMR (400 MHz, CDCl₃) δ 7.88 (d, J = 8.4 Hz, 2H), 159.80, 142.69, 135.59, 131.93, 129.58, 128.23, 120.76, 115.00,

7.42 (d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 2H), 6.84 (d, J = 8.4 Hz, 2H), 114.31, 111.48, 55.18, 40.30, 30.09.

J. Name., 2013, 00, 1-3 | 17

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Page 18 of 23

ARTICLE

Journal Name

1-(4-chlorophenyl)-3-(3-methoxyphenyl)propan-1-one

(5ce)³¹: 198.38, 138.03, 135.75, 132.00, 129.68, 129.35, 128.39, 40.67, 29.70,

View Article Online

DOI: 10.1039/D0DT03748F

White solid, Yield: Co1 (241.12 mg, 88%), Co2 (232.90 mg, 85%), Co3 21.13.

(221.94 mg, 81%).¹H NMR (400 MHz, CDCl₃) δ 7.89 (d, J = 8.7 Hz, 2H), 1-(4-chlorophenyl)-3-(p-tolyl)propan-1-one (5de)⁵⁴: Off-white solid,

7.42 (d, J = 8.7 Hz, 2H), 7.22 (t, J = 7.8 Hz, 1H), 6.83 (d, J = 7.5 Hz, 1H), Yield: Co1 (224.46 mg, 87%), Co2 (221.88 mg, 86%), Co3 (216.72 mg,

6.79 (s, 1H), 6.76 (d, J = 8.6 Hz, 1H), 3.80 (s, 3H), 3.29 (t, J = 7.6 Hz, 84%).¹H NMR (400 MHz, CDCl₃) δ 7.90 (d, J = 8.7 Hz, 2H), 7.43 (d, J =

2H), 3.06 (t, J = 7.1 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 198.04, 8.6 Hz, 2H), 7.14 (d, J = 4.3 Hz, 4H), 3.26 (t, J = 7.7 Hz, 2H), 3.01 (t, J =

159.83, 142.78, 139.60, 135.21, 129.60, 129.01, 120.83, 114.35, 7.4 Hz, 2H), 2.34 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 198.19, 139.55,

111.51, 55.26, 40.43, 30.15.

138.05, 135.82, 135.27, 129.56, 129.35, 129.01, 128.39, 40.68, 29.72,

(5cf)³¹: 21.13.

1-(4-fluorophenyl)-3-(3-methoxyphenyl)propan-1-one

Yellow oil, Yield: Co1 (216.72 mg, 84%), Co2 (211.56 mg, 82%), Co3 1-(4-fluorophenyl)-3-(p-tolyl)propan-1-one (5df)⁵²: yellow oil, Yield:

(206.4 mg, 80%). ¹H NMR (400 MHz, CDCl₃) δ 7.98 (d, J = 8.9 Hz, 2H), Co1 (205.7 mg, 85%), Co2 (200.86 mg, 83%), Co3 (196.02 mg, 81%).

7.22 (t, J = 7.8 Hz, 1H), 7.12 (t, J = 8.7 Hz, 2H), 6.84 (d, J = 8.1 Hz, 1H), ¹H NMR (400 MHz, CDCl₃) δ 8.00 – 7.96 (m, 2H), 7.14 (d, J = 2.4 Hz,

6.80 (s, 1H), 6.76 (d, J = 8.2 Hz, 1H), 3.80 (s, 3H), 3.30(t, J = 7.6 Hz, 3H), 7.11 (d, J = 9.2 Hz, 3H), 3.24 (t, J = 8.1 Hz, 2H), 3.04 (t, J = 7.4 Hz,

2H), 3.06 (t, J = 7.4 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 197.69, 2H), 2.32 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 197.85, 138.10, 135.80,

167.08, 164.55, 159.81, 142.86, 133.32, 130.70, 129.70, 120.80, 133.39, 130.74, 129.31, 128.36, 115.87, 115.65, 40.62, 29.76, 21.09.

115.98, 114.36, 111.49, 55.27, 40.36, 30.20.

1-(2-chlorophenyl)-3-(p-tolyl)propan-1-one (5dg): Off-white solid,

1-phenyl-3-(p-tolyl)propan-1-one (5da)⁵⁰: Yellow oil, Yield: Co1 Yield: Co1 (216.72 mg, 84%), Co2 (211.56 mg, 82%), Co3 (206.4 mg,

(199.36 mg, 89%), Co2 (197.12 mg, 88%), Co3 (194.88 mg, 87%). ¹H 80%). H NMR (400 MHz, CDCl₃) δ 7.43 – 7.39 (m, 2H), 7.36 (d, J =

1

NMR (400 MHz, CDCl₃) δ 7.99 (d, J = 10.0 Hz, 2H), 7.58 (t, J = 7.7 Hz, 8.2Hz, 1H), 7.32 (d, J = 1.7 Hz, 1H), 7.29 (d, J = 7.1 Hz, 1H), 7.11 (d, J =

1H), 7.47 (t, J = 8.0 Hz, 2H), 7.16 (d, J = 8.7 Hz, 4H), 3.33 (t, J = 7.7 Hz, 2.2 Hz, 4H), 3.25 (t, J = 7.8 Hz, 2H), 3.04 (t, J = 7.5 Hz, 2H), 2.32 (s, 3H).

2H), 3.09 (t, J = 8.0 Hz, 2H), 2.35 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ ¹³C NMR (101 MHz, CDCl₃) δ 202.78, 139.47, 137.75, 135.77, 130.99,

199.46, 138.31, 136.98, 135.73, 133.16, 129.46, 128.72, 128.43, 129.36, 128.35, 127.09, 44.81, 29.80, 21.10.

128.16, 40.73, 29.82, 21.14.

1-(3-methoxyphenyl)-3-(p-tolyl)propan-1-one (5dh)⁵¹: Yellow oil,

1-(4-methoxyphenyl)-3-(p-tolyl)propan-1-one (5db)⁵¹: Yellow oil, Yield: Co1 (218.44 mg, 86%), Co2 (213.36 mg, 84%), Co3 (208.28 mg,

Yield: Co1 (233.68 mg, 92%), Co2 (228.6 mg, 90%), Co3 (223.52 mg, 82%). ¹H NMR (400 MHz, CDCl₃) δ 7.55 (d, J = 7.7 Hz, 1H), 7.50 (s, 1H),

88%). ¹H NMR (400 MHz, CDCl₃) δ 7.96 (d, J = 8.9 Hz, 2H), 7.19 – 7.11 7.37 (t, J = 7.9 Hz, 1H), 7.16 (t, J = 7.9 Hz, 3H), 7.11 (d, J = 8.6 Hz, 2H),

(m, 4H), 6.94 (d, J = 8.9 Hz, 2H), 3.87 (s, 3H), 3.27 (t, J = 7.5 Hz, 2H), 3.86 (s, 3H), 3.27 (t, J = 8.1 Hz, 2H), 3.07 (t, J = 7.4 Hz, 2H), 2.34 (s,

3.04 (t, J = 7.7 Hz, 2H), 2.35 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 3H). ¹³C NMR (101 MHz, CDCl₃) δ 199.27, 159.92, 138.27, 135.76,

198.04, 163.53, 138.48, 135.65, 130.42, 130.08, 129.30, 128.42, 132.52, 129.80, 129.50, 128.44, 120.81, 119.71, 112.28, 55.53, 40.84,

113.82, 55.55, 40.38, 30.02, 21.13.

29.85, 21.14.

1,3-di-p-tolylpropan-1-one (5dc)⁵²: Yellow oil, Yield: Co1 (211.82 mg, 3-(4-chlorophenyl)-1-phenylpropan-1-one (5ea)³¹: White solid,

89%), Co2 (207.06 mg, 87%), Co3 (199.92 mg, 84%).¹H NMR (400 Yield: Co1 (207.4 mg, 85%), Co2 (202.52 mg, 83%), Co3 (197.64 mg,

MHz, CDCl₃) δ 7.86 (d, J = 8.2 Hz, 2H), 7.25 (d, J = 7.7 Hz, 2H), 7.13 (q, 81%).¹H NMR (400 MHz, CDCl₃) δ 7.95 (d, J = 7.0 Hz, 2H), 7.56 (d, J =

J = 8.1 Hz, 4H), 3.28 (t, J = 7.6 Hz, 2H), 3.05 (t, J = 7.4 Hz, 2H), 2.41 (s, 7.5 Hz, 1H), 7.45 (d, J = 7.5 Hz, 2H), 7.26 (d, J = 8.4 Hz, 2H), 7.19 (d, J

3H), 2.33 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 199.15, 143.89, 138.38, = 8.5 Hz, 3H), 3.28 (t, J = 7.6 Hz, 2H), 3.05 (t, J = 7.5 Hz, 2H). ¹³C NMR

135.67, 134.48, 129.32, 128.32, 40.61, 29.88, 21.73, 21.10.

(101 MHz, CDCl₃) δ 198.93, 139.82, 136.84, 133.26, 131.96, 129.91,

1-(4-bromophenyl)-3-(p-tolyl)propan-1-one (5dd)⁵³: White soild, 128.70, 128.09, 40.22, 29.46.

Yield: Co1 (265.76 mg, 88%), Co2 (259.72 mg, 86%), Co3 (253.68 mg, 3-(4-chlorophenyl)-1-(4-methoxyphenyl)propan-1-one

(5eb)³¹:

84%). ¹H NMR (400 MHz, CDCl₃) δ 7.81 (s, 1H), 7.60 (d, J = 8.4 Hz, 2H), White solid, Yield: Co1 (235.64 mg, 86%), Co2 (232.90 mg, 85%), Co3

7.14 (t, J = 6.1 Hz, 4H), 7.03 (d, J = 2.0 Hz, 1H), 3.25 (t, J = 7.6 Hz, 2H), (227.42 mg, 83%).¹H NMR (400 MHz, CDCl₃) δ 7.93 (d, J = 8.9 Hz, 2H),

3.04 (t, J = 7.7 Hz, 2H), 2.34 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 7.25 (d, J = 8.3 Hz, 2H), 7.18 (d, J = 8.5 Hz, 2H), 6.93 (d, J = 8.9 Hz, 2H),

3.87 (s, 3H), 3.23 (t, J = 7.6 Hz, 2H), 3.03 (t, J = 7.5 Hz, 2H). ¹³C NMR

18 | J. Name., 2012, 00, 1-3

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Journal Name

ARTICLE

(126 MHz, CDCl₃) δ 197.42, 163.55, 139.93, 131.82, 130.29, 129.83, 6.92 (d, J = 9.0 Hz, 2H), 3.85 (s, 3H), 3.22 (t, J = 7.7 Hz, 2H), 3.02 (t, J

View Article Online

128.57, 115.00, 113.78, 55.47, 39.76, 29.58.

= 7.6 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ ^D19^O7^I:.3¹⁰3^.,¹⁰1³6⁹3^/.^D6⁰2^D, ^T1⁰4³3⁷.⁴6⁸5^F,

3-(4-chlorophenyl)-1-(p-tolyl)propan-1-one (5ec)³¹: Off-white solid, 134.25, 130.38, 129.87, 128.69, 126.59, 126.34, 113.84, 55.56, 39.70,

Yield: Co1 (216.72 mg, 84%), Co2 (211.56 mg, 82%), Co3 (208.98 mg, 29.91.

81%). ¹H NMR (500 MHz, CDCl₃) δ 7.88 (d, J = 8.2 Hz, 2H), 7.30 – 7.27 3-(3-chlorophenyl)-1-(p-tolyl)propan-1-one (5fc)³¹: Light yellow

(m, 4H), 7.21 (d, J = 8.4 Hz, 2H), 3.28 (t, J = 7.6 Hz, 2H), 3.06 (t, J = 7.4 solid, Yield: Co1 (216.72 mg, 84%), Co2 (211.56 mg, 82%), Co3

Hz, 1H), 2.44 (s, 1H). ¹³C NMR (101 MHz, CDCl₃) δ 198.60, 144.06, (201.24 mg, 78%). ¹H NMR (400 MHz, CDCl₃) δ 7.87 (d, J = 8.1 Hz, 2H),

139.94, 134.38, 131.90, 130.44, 129.92, 129.41, 128.66, 128.23, 7.27 (s, 1H), 7.26 (s, 1H), 7.23 – 7.19 (m, 2H), 7.16 (t, J = 7.9 Hz, 2H),

40.10, 29.55, 21.73.

3.27 (t, J = 7.6 Hz, 2H), 3.05 (t, J = 7.6 Hz, 2H), 2.42 (s, 3H). ¹³C NMR

1-(4-bromophenyl)-3-(4-chlorophenyl)propan-1-one (5ed)³¹: Light (101 MHz, CDCl₃) δ 198.42, 144.08, 143.58, 134.32, 129.48, 128.83,

yellow solid, Yield: Co1 (256.80 mg, 80%), Co2 (250.38 mg, 78%), Co3 128.49, 128.15, 127.02, 126.38, 125.96, 39.95, 29.82, 21.69.

(243.96 mg, 76%). ¹H NMR (400 MHz, CDCl₃) δ 7.80 (d, J = 8.6 Hz, 2H), 1-(4-bromophenyl)-3-(3-chlorophenyl)propan-1-one (5fd)³¹: White

7.59 (d, J = 8.6 Hz, 2H), 7.26 (d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.1 Hz, 2H), solid, Yield: Co1 (240.75 mg, 75%), Co2 (234.33 mg, 73%), Co3

3.25 (t, J = 7.1 Hz, 2H), 3.03 (t, J = 7.5 Hz, 2H). ¹³C NMR (101 MHz, (218.28 mg, 68%).¹H NMR (500 MHz, CDCl₃) δ 7.81 (d, J = 7.3 Hz, 1H),

CDCl₃) δ 197.86, 139.57, 135.52, 132.04, 131.55, 130.81, 130.45, 7.59 (d, J = 7.4 Hz, 2H), 7.38 (d, J = 4.8 Hz, 1H), 7.23 (d, J = 8.0 Hz, 2H),

129.89, 129.61, 128.72, 128.44, 40.18, 29.35.

7.18 (d, J = 8.3 Hz, 1H), 7.12 (d, J = 7.5 Hz, 1H), 3.25 (t, J = 7.5 Hz, 13H),

1,3-bis(4-chlorophenyl)propan-1-one (5ee)³¹: Light yellow solid, 3.04 (t, J = 7.5 Hz, 13H). ¹³C NMR (126 MHz, CDCl₃) δ 197.62, 143.11,

Yield: Co1 (216.84 mg, 78%), Co2 (214.06 mg, 77%), Co3 (208.5 mg, 135.42, 134.29, 131.97, 131.53, 130.77, 129.83, 129.55, 128.58,

75%).¹H NMR (500 MHz, CDCl₃) δ 7.93 (d, J = 7.7 Hz, 2H), 7.47 (d, J = 128.38, 126.71, 126.45, 39.96, 29.56.

7.7 Hz, 2H), 7.30 (d, J = 7.4 Hz, 2H), 7.22 (d, J = 7.8 Hz, 2H), 3.29 (t, J 3-(3-chlorophenyl)-1-(4-chlorophenyl)propan-1-one (5fe)³¹: White

= 7.5 Hz, 2H), 3.08 (t, J = 7.4 Hz, 2H). ¹³C NMR (126 MHz, CDCl₃) δ solid, Yield: Co1 (202.94 mg, 73%), Co2 (197.38 mg, 71%), Co3

197.60, 139.58, 135.05, 131.98, 130.44, 129.82, 129.43, 128.98, (183.48 mg, 66%). ¹H NMR (400 MHz, CDCl₃) δ 7.89 (d, J = 8.6 Hz, 2H),

128.65, 115.00, 40.12, 29.29.

7.43 – 7.41 (m, 1H), 7.23 (d, J = 7.0 Hz, 2H), 7.19 (s, 1H), 7.13 (d, J =

3-(4-chlorophenyl)-1-(4-fluorophenyl)propan-1-one (5ef)³¹: Off- 7.1 Hz, 2H), 3.26 (d, J = 8.1 Hz, 2H), 3.05 (d, J = 7.7 Hz, 2H). ¹³C NMR

white solid, Yield: Co1 (201.74 mg, 77%), Co2 (199.12 mg, 76%), Co3 (101 MHz, CDCl₃) δ 197.52, 143.20, 139.72, 135.08, 134.35, 129.52,

(196.5 mg, 75%). ¹H NMR (400 MHz, CDCl₃) δ 7.97 (d, J = 8.9 Hz, 2H), 128.80, 128.51, 126.63, 126.34, 40.05, 29.64.

7.26 (d, J = 2.7 Hz, 1H), 7.25 (d, J = 2.9 Hz, 1H), 7.18 (d, J = 8.3 Hz, 2H), 3-(3-chlorophenyl)-1-(4-fluorophenyl)propan-1-one (5ff)³¹: Pale

7.12 (t, J = 8.6 Hz, 2H), 3.25 (t, J = 7.6 Hz, 2H), 3.03 (t, J = 7.5 Hz, 2H). Yellow solid, Yield: Co1 (186.02 mg, 71%), Co2 (180.78 mg, 69%), Co3

¹³C NMR (101 MHz, CDCl₃) δ 197.34, 167.13, 164.59, 139.66, 133.25, (167.68 mg, 64%).¹H NMR (400 MHz, CDCl₃) δ 7.99 (d, J = 5.4 Hz, 1H),

132.01, 130.73, 129.92, 128.73, 115.99, 40.16, 29.40.

7.97 (d, J = 5.4 Hz, 1H), 7.25 – 7.20 (m, 2H), 7.18 (d, J = 8.1 Hz, 1H),

3-(3-chlorophenyl)-1-phenylpropan-1-one (5fa)³¹: White solid, 7.12 (t, J = 8.7 Hz, 2H), 3.26 (t, J = 7.7 Hz, 2H), 3.04 (t, J = 7.6 Hz, 2H).

Yield: Co1 (204.96 mg, 84%), Co2 (200.08 mg, 82%), Co3 (195.20 mg, ¹³C NMR (101 MHz, CDCl₃) δ 197.16, 167.14, 164.60, 143.27, 134.34,

80%). ¹H NMR (400 MHz, CDCl₃) δ 7.96 (d, J = 7.1 Hz, 2H), 7.57 (t, J = 133.23, 130.74, 126.94, 116.22, 39.99, 29.69.

7.4 Hz, 1H), 7.46 (t, J = 7.9 Hz, 2H), 7.25 (d, J = 3.7 Hz, 1H), 7.22 (d, J 3-(3,4-dimethoxyphenyl)-1-phenylpropan-1-one (5ga)³¹: Yellow oil,

= 7.2 Hz, 1H), 7.19 (d, J = 8.0Hz, 1H), 7.14 (d, J = 7.4 Hz, 1H), 3.30 (t, J Yield: Co1 (261.9 mg, 97%), Co2 (256.5 mg, 95%), Co3 (243.0 mg,

= 7.6 Hz, 2H), 3.06 (t, J = 7.6 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 90%). ¹H NMR (500 MHz, CDCl₃) δ 7.95 (d, J = 7.9 Hz, 2H), 7.55 (t, J =

198.79, 143.44, 136.78, 134.31, 133.30, 129.87, 128.71, 128.12, 7.2 Hz, 1H), 7.45 (t, J = 7.5 Hz, 2H), 6.78 (d, J = 7.9 Hz, 2H), 3.86 (s,

126.81, 126.43, 40.09, 29.74.

3H), 3.85 (s, 3H), 3.28 (t, J = 7.6 Hz, 2H), 3.02 (t, J = 7.6 Hz, 2H). ¹³

C

3-(3-chlorophenyl)-1-(4-methoxyphenyl)propan-1-one (5fb)³¹: Off- NMR (126 MHz, CDCl₃) δ 199.40, 148.93, 147.42, 136.92, 133.93,

white solid Yield: Co1 (232.90 mg, 85%), Co2 (227.42 mg, 83%), Co3 133.07, 128.62, 128.05, 120.20, 115.00, 111.89, 111.39, 55.95, 55.85,

(221.94 mg, 81%). ¹H NMR (400 MHz, CDCl₃) δ 7.93 (d, J = 8.9 Hz, 2H), 40.69, 29.82.

7.25 (d, J = 7.9 Hz, 2H), 7.16 (d, J = 8.1 Hz, 1H), 7.13 (d, J = 7.1 Hz, 1H),

J. Name., 2013, 00, 1-3 | 19

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Journal Name

3-(3,4-dimethoxyphenyl)-1-(4-methoxyphenyl)propan-1-one

Propiophenone (5ha)³¹: Yellow liquid, Yield: Co1 (101.84 mg, 76%),

View Article Online

DOI: 10.1039/D0DT03748F

(5gb)³¹: Yellow oil, Yield: Co1 (294.0 mg, 98%), Co2 (288.0 mg, 96%), Co2 (96.48 mg, 72%), Co3 (92.46 mg, 69%).¹H NMR (500 MHz, CDCl3)

Co3 (276.0 mg, 92%). ¹H NMR (500 MHz, CDCl₃) δ 7.93 (d, J = 8.1 Hz, δ 7.97 (d, J = 7.1 Hz, 2H), 7.58 – 7.54 (m, 1H), 7.46 (t, J = 7.6 Hz, 2H),

2H), 6.91 (d, J = 8.1 Hz, 2H), 6.79 (t, J = 8.1 Hz, 3H), 3.86 (s, 3H), 3.85 3.01 (q, J = 7.2 Hz, 2H), 1.24 (t, J = 7.2 Hz, 3H). ¹³C NMR (126 MHz,

(s, 6H), 3.22 (t, J = 7.6 Hz, 2H), 3.00 (t, J = 7.6 Hz, 2H). ¹³C NMR (126 CDCl3) δ 200.81, 136.90, 132.86, 128.53, 127.95, 31.76, 8.23.

MHz, CDCl₃) δ 197.99, 163.46, 148.90, 147.38, 134.10, 130.32, 1-phenylbutan-1-one (5hb)³¹: Yellow liquid, Yield: Co1 (115.44 mg,

130.02, 120.18, 115.00, 113.73, 111.88, 111.36, 55.94, 55.46, 40.35, 78%), Co2 (125.80 mg, 75%), Co3 (105.08 mg, 81%). ¹H NMR (500

30.03.

MHz, CDCl₃) δ 7.97 (d, J = 7.1 Hz, 2H), 7.55 (t, J = 7.4 Hz, 1H), 7.46 (t,

3-(3,4-dimethoxyphenyl)-1-(p-tolyl)propan-1-one (5gc)³¹: Yellow J = 7.6 Hz, 2H), 2.95 (t, J = 7.3 Hz, 2H), 1.78 (dd, J = 14.7, 7.4 Hz, 2H),

oil, Yield: Co1 (266.96 mg, 94%), Co2 (261.28 mg, 92%), Co3 (258.44 1.02 (t, J = 7.4 Hz, 3H). ¹³C NMR (126 MHz, CDCl₃) δ 200.38, 137.09,

mg, 91%). ¹H NMR (400 MHz, CDCl₃) δ 7.84 (d, J = 8.2 Hz, 2H), 7.21 (d, 132.85, 128.53, 128.02, 40.49, 17.76, 13.88.

J = 7.8 Hz, 2H), 6.77 (s, 3H), 3.84 (s, 3H), 3.82 (s, 3H), 3.23 (t, J = 7.6 General procedure for dehydrogenative cyclization of 2-amino

Hz, 2H), 3.01(t, J = 7.4 Hz, 2H), 2.37 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) benzyl alcohols with ketones

δ 199.07, 148.97, 147.45, 143.87, 134.51, 134.10, 129.35, 128.23, To a 10mL, clean, oven-dried, screw cap reaction tube containing 1

120.27, 111.95, 111.44, 55.89, 55.98, 40.60, 29.96, 21.69.

mmol of o-amino benzyl alcohols, 1 mmol ketones in dry toluene (2

1-(4-bromophenyl)-3-(3,4-dimethoxyphenyl)propan-1-one (5gd)³¹: mL) solvent was mixed with 2 mol % catalyst, 0.5 mmol KO^tBu were

White solid, Yield: Co1 (313.2 mg, 90%), Co2 (306.24 mg, 88%), Co3 reacted in inert condition. The reaction mixture was heated at 110 °C

(299.28 mg, 86%). ¹H NMR (400 MHz, CDCl₃) δ 7.79 (d, J = 8.6 Hz, 2H), with constant stirring in a preheated oil bath for 24 h. The resulting

7.57 (d, J = 8.6 Hz, 2H), 6.79 (d, J = 8.6 Hz, 1H), 6.77 (d, J = 1.8 Hz, 1H), solution was then filtered off through Whatman 41 filter paper. The

6.76 – 6.75 (m, 1H), 3.85 (s, 3H), 3.84 (s, 3H), 3.23 (t, J = 7.6 Hz, 2H), filtrate was dried under reduced pressure, and the organic product

2.99 (t, J = 7.6 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 198.37, 149.02, was extracted by a solvent extraction technique using a water/ethyl

147.56, 135.68, 133.72, 131.97, 129.64, 128.28, 120.25, 111.93, acetate solvent mixture. The organic layer was collected and

111.46, 90.06, 56.06, 55.89, 40.72, 29.78.

removed through rotary evaporator. The residue was then purified

1-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)propan-1-one (5ge)³¹: by 100-200 mesh column chromatography on silica gel (eluent:

Off-white solid, Yield: Co1 (270.56 mg, 89%), Co2 (264.48 mg, 87%), hexane /ethyl acetate) to get the derivatives of quinolines. The

Co3 (258.40 mg, 85%). ¹H NMR (400 MHz, CDCl₃) δ 7.85 (d, J = 8.7 Hz, isolated products were authenticated by ¹H and ¹³C NMR spectra

2H), 7.38 (d, J = 8.6 Hz, 2H), 6.77 – 6.74 (m, 3H), 3.84 (s, 3H), 3.82 (s, which were displayed in Supporting Information (Figures S139-S162).

3H), 3.22 (t, J = 7.6 Hz, 2H), 2.98 (t, J = 7.6 Hz, 2H). ¹³C NMR (101 MHz, 2-phenylquinoline (7aa)^20b: White solid, Yield: Co1 (184.5 mg, 90%),

CDCl₃) δ 198.14, 148.99, 147.52, 139.50, 135.26, 133.73, 129.52, Co2 (180.4 mg, 88%), Co 3 (172.2 mg, 84%).¹H NMR (400 MHz, CDCl₃)

129.02, 120.25, 111.90, 111.42, 55.94, 55.86, 40.70, 29.77.

δ 8.23 (d, J = 8.7 Hz, 1H), 8.17 (d, J = 8.4 Hz, 3H), 7.89 (d, J = 8.7 Hz,

3-(3,4-dimethoxyphenyl)-1-(4-fluorophenyl)propan-1-one (5gf)³¹: 1H), 7.84 (d, J = 9.9 Hz, 1H), 7.74 (d, J = 8.7 Hz, 1H), 7.57 – 7.50 (m,

Yellow liquid, Yield: Co1 (250.56 mg, 87%), Co2 (244.80 mg, 85%), 3H), 7.47 (d, J = 7.4 Hz, 1H). ¹³C NMR (101 MHz, CDCl₃) δ 157.50,

Co3 (233.28 mg, 81%). ¹H NMR (400 MHz, CDCl₃) δ 7.97 (m, 2H), 7.11 148.36, 139.78, 136.90, 129.77, 129.41, 128.94, 127.62, 127.27,

(t, J = 8.6 Hz, 2H), 6.77 (m, 3H), 3.86 (s, 3H), 3.85 (s, 3H), 3.24 (t, J = 126.37, 119.14.

8.0 Hz, 2H), 3.00 (t, J = 7.6 Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 2-(4-methoxyphenyl)quinoline (7ab)^20b: White solid, Yield: Co1

197.85, 167.06, 164.52, 148.98, 147.50, 133.81, 133.40, 130.73, (216.2 mg, 92%), Co2 (211.5 mg, 90%), Co 3 (206.8 mg, 88%).¹H NMR

120.24, 116.04, 115.78, 111.88, 111.38,56.00, 55.91, 40.70, 29.85.

(E)-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (3ca)³¹:¹H NMR

(500 MHz, CDCl₃) δ 8.05 (d, J = 8.5 Hz, 2H), 7.80 (d, J = 15.6 Hz, 1H),

7.64 (s, 2H), 7.55 (d, J = 15.6 Hz, 1H), 7.41 (m, 3H), 6.99 (d, J = 8.5 Hz,

2H), 3.89 (s, 3H).

(400 MHz, CDCl₃) δ 8.18 (d, J = 8.6 Hz, 1H), 8.16 – 8.12 (m, 3H), 7.83

(d, J = 8.6 Hz, 1H), 7.80 (d, J = 8.1 Hz, 1H), 7.71 (d, J = 8.5 Hz, 1H), 7.50

(d, J = 8.1 Hz, 1H), 7.05 (d, J = 8.9 Hz, 2H), 3.89 (s, 3H). ¹³C NMR (101

MHz, CDCl₃) δ 160.90, 157.01, 148.37, 136.73, 132.34, 129.66,

128.98, 127.52, 126.99, 125.98, 118.66, 114.32, 55.49.

20 | J. Name., 2012, 00, 1-3

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2-(p-tolyl)quinoline (7ac)^20b: White solid, Yield: Co1 (199.29 mg, 2-(pyridin-4-yl)quinoline (7ai)³¹: Yellow solid, Yield: Co1 (183.34 mg,

View Article Online

DOI: 10.1039/D0DT03748F

91%), Co2 (194.91 mg, 89%), Co3 (190.53 mg, 87%).¹H NMR (400 89%), Co2 (175.10 mg, 85%), Co3 (170.98 mg, 83%). ¹H NMR (500

MHz, CDCl₃) δ 8.21 – 8.16 (m, 3H), 8.08 – 8.07 (m, 2H), 7.86 (d, J = 2.9 MHz, CDCl₃) δ 8.72 (d, J = 4.3 Hz, 1H), 8.64 (d, J = 7.9 Hz, 1H), 8.54 (d,

Hz, 1H), 7.83 – 7.81 (m, 1H), 7.74 – 7.70 (m, 2H), 7.51 (d, J = 8.1 Hz, J = 8.6 Hz, 1H), 8.26 (d, J = 8.6 Hz, 1H), 8.17 (d, J = 8.4 Hz, 1H), 7.84

2H), 7.33 (s, 1H), 2.44 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ 157.45, (d, J = 7.7 Hz, 2H), 7.71 (t, J = 7.6 Hz, 1H), 7.52 (t, J = 7.5 Hz, 1H), 7.33

148.36, 139.51, 136.87, 129.72, 127.54, 127.19, 126.17, 118.99, (t, J = 7.2 Hz, 1H).¹³C NMR (126 MHz, CDCl₃) δ 156.37, 156.19, 149.19,

21.47.

147.88, 136.89, 129.84, 129.57, 128.27, 127.64, 126.77, 124.04,

2-(4-bromophenyl)quinoline (7ad)^20b: Off-white solid, Yield: Co1 121.85, 118.98, 115.00.

(248.16 mg, 88%), Co2 (242,52 mg, 86%), Co3 (236.88 mg, 84%).¹H 2-(naphthalen-1-yl)quinoline (7aj)^20b: White solid, Yield: Co1 (232.05

NMR (400 MHz, CDCl₃) δ 8.23 (d, J = 8.5 Hz, 1H), 8.16 (d, J = 8.5 Hz, mg, 91%), Co2 (229.50 mg, 90%), Co3 (226.95 mg, 89%). ¹H NMR (500

1H), 8.08 – 8.04 (m, 2H), 7.85 – 7.82 (m, 2H), 7.74 (d, J = 8.4 Hz, 1H), MHz, CDCl₃) δ 8.62 (s, 1H), 8.38 (d, J = 8.6 Hz, 1H), 8.25 (m, 2H), 8.03

7.67 – 7.63 (m, 2H), 7.54 (d, J = 8.1 Hz, 1H). ¹³C NMR (101 MHz, CDCl₃) (m, 3H), 7.93 – 7.84 (m, 2H), 7.76 (t, J = 7.6 Hz, 1H), 7.55 (t, J = 7.4 Hz,

δ 156.16, 148.32, 138.59, 137.10, 132.07, 129.87, 129.19, 127.59, 3H). ¹³C NMR (126 MHz, CDCl₃) δ 157.20, 148.40, 136.91, 133.88,

127.33, 126.63, 124.02, 118.63.

133.53, 129.75, 128.85, 128.60, 127.74, 127.52, 127.21, 125.09,

2-(4-chlorophenyl)quinoline (7ae)^20b: Off-white solid, Yield: Co1 119.19.

(205.54 mg, 86%), Co2 (200.76 mg, 84%), Co3 (193.59 mg, 81%).¹H 5,6-dihydrobenzo[c]acridine (7ak)^20b: White solid, Yield: Co1 (207.90

NMR (400 MHz, CDCl₃) δ 8.23 (d, J = 8.7 Hz, 1H), 8.16 (d, J = 8.5 Hz, mg, 90%), Co2 (205.59 mg, 89%), Co3 (203.28 mg, 88%).¹H NMR (400

1H), 8.14 – 8.08 (m, 2H), 7.83 (d, J = 8.6 Hz, 2H), 7.74 (d, J = 8.6 Hz, MHz, CDCl₃) δ 8.64 (d, J = 7.6 Hz, 1H), 8.19 (d, J = 8.4 Hz, 1H), 7.87 (s,

1H), 7.57 – 7.53 (m, 1H), 7.53 – 7.47 (m, 2H). ¹³C NMR (101 MHz, 1H), 7.75 – 7.64 (m, 2H), 7.47 (d, J = 7.4 Hz, 2H), 7.40 (t, J = 6.8 Hz,

CDCl₃) δ 156.11, 148.32, 138.14, 137.06, 135.65, 129.86, 129.11, 1H), 7.29 (d, J = 7.4 Hz, 1H), 3.13 – 3.05 (m, 2H), 3.04 – 2.97 (m, 2H).

128.91, 127.58, 127.30, 126.59, 118.66.

¹³C NMR (101 MHz, CDCl₃) δ 153.51, 147.74, 139.56, 134.82, 133.85,

2-(4-fluorophenyl)quinoline (7af)³¹: Pale-yellow solid, Yield: Co1 132.00, 132.00, 129.28, 128.80, 127.99, 127.53, 127.27, 126.16,

(189.55 mg, 85%), Co2 (185.09 mg, 83%), Co3 (178.4 mg, 80%).¹H 28.94, 28.50.

NMR (400 MHz, CDCl₃) δ 8.22 (d, J = 8.7 Hz, 1H), 8.19 – 8.14 (m, 3H), 1,2,3,4-tetrahydroacridine (7al)^20b: Colourless oil, Yield: Co1 (162.87

7.84 (s, 2H), 7.73 (d J = 8.4 Hz, 1H), 7.56 – 7.51 (m, 1H), 7.21 (t, J = 8.7 mg, 89%), Co2 (159.21 mg, 87%), Co3 (157.38 mg, 86%).¹H NMR (400

Hz, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 165.13, 162.65, 156.34, 148.30, MHz, CDCl₃) δ 7.96 (d, J = 8.4 Hz, 1H), 7.73 (s, 1H), 7.64 (d, J = 8.1 Hz,

137.01, 135.92, 129.65, 127.57, 127.16, 126.42, 118.72, 116.00, 1H), 7.57 (d, J = 8.4 Hz, 1H), 7.39 (d, J = 8.1 Hz, 1H), 3.10 (t, J = 6.6 Hz,

115.70.

2H), 2.92 (t, J = 6.3 Hz, 2H), 1.96 (t, J = 6.4 Hz, 2H), 1.88 – 1.81 (m,

2-(4-iodophenyl)quinoline (7ag)³¹: White solid, Yield: Co1 (293.7 mg, 2H). ¹³C NMR (101 MHz, CDCl₃) δ 159.34, 146.64, 135.06, 131.01,

89%), Co2 (287.1 mg, 87%), Co3 (283.8 mg, 86%).¹H NMR (400 MHz, 128.43, 128.19, 128.00, 127.11, 125.54, 33.62, 29.30, 23.29.

CDCl₃) δ 8.21 (d, J = 8.6 Hz, 1H), 8.15 (d, J = 8.5 Hz, 1H), 8.04 (d, J =

Conflicts of interest

There are no conflicts to declare.

8.5 Hz, 2H), 7.82 (d, J = 8.4 Hz, 2H), 7.73 (t, J = 7.7 Hz, 1H), 7.64 (d, J

= 8.5 Hz, 2H), 7.52 (d, J = 7.6 Hz, 1H). ¹³C NMR (101 MHz, CDCl₃) δ

156.15, 148.32, 138.59, 137.10 , 132.07, 129.97, 129.78, 129.19,

127.59, 127.33, 126.63, 124.02, 118.62.

Acknowledgements

KG is thankful to CSIR, New Delhi 01(2942)/18/EMR-II dated 01-05-

2018) for ﬁnancial assistance. AS and AM are thankful to MHRD for

their fellowship. MJ is thankful to DST/INSPIRE fellowship for

financial support. We are thankful to Kumud Pandav for his help.

2-(pyridin-2-yl)quinoline (7ah)³¹: Yellow solid, Yield: Co1 (181.28 mg,

88%), Co2 (175.1 mg, 85%), Co3 (170.98 mg, 83%).¹H NMR (400 MHz,

CDCl₃) δ 8.74 (d, J = 5.9 Hz, 1H), 8.66 (d, J = 8.5 Hz, 1H), 8.55 (s, 1H),

8.28 (d, J = 9.0 Hz, 1H), 8.18 (d, J = 4.4 Hz, 1H), 7.86 (d, J = 13.5 Hz,

2H), 7.73 (d, J = 8.3 Hz, 1H), 7.55 (t, J = 8.0 Hz, 1H), 7.37 – 7.33 (m,

1H). ¹³C NMR (101 MHz, CDCl₃) δ 156.34, 149.26, 148.01, 137.05,

129.65, 128.34, 127.71, 126.85, 124.07, 121.94, 119.06.

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Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines

DOI: 10.1039/d0dt03748f

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