Table 2 Screening of reaction conditions for cross-coupling QMA of 4a and 5-bromoresorcinol 2ja.

From: Bayesian optimization-driven parallel-screening of multiple parameters for the flow synthesis of biaryl compounds

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Entry

Micro mixer

2j (equiv.)

TfOH (mol%)

Temp. (˚C)

Conc. of 4a (M)

Flow rate (mL/min)

Residence time (min)

NMR yieldb (%)

1

Comet Xc

2.0

1.0

60

0.05

0.05

24

14

2

Comet X

3.0

0.5

40

0.01

0.2

6

35

3

β-typed

1.0

2.0

60

0.01

0.1

13.5

11

4

β-type

3.0

0.5

20

0.1

0.1

13.5

52

5

T-shapede

1.0

2.0

40

0.05

0.05

16

4

6

T-shaped

2.0

1.0

20

0.1

0.2

4

29

7

Comet X

3.0

0.29

25

0.14

0.048

25

20

8

β-type

3.5

0.25

15

0.035

0.087

15.5

58

9

T-shaped

3.5

0.98

30

0.15

0.022

36

19

10

Comet X

3.4

0.37

35

0.056

0.13

9

10

11

β-type

2.4

0.34

15

0.019

0.041

33

40

12

T-shaped

2.4

0.73

15

0.011

0.060

13’

19

13

β-type

3.2

0.25

15

0.068

0.062

22

20

14

β-type

3.5

0.53

15

0.067

0.097

14

43

15

β-type

3.2

0.35

30

0.044

0.068

20

69 (66)c

  1. aReaction conditions: 4a (0.065 mmol), 2j, and TfOH, in degassed dry toluene/EtOAc (10/1).
  2. b1,3,5-Trimethoxybenzene was used as a standard.
  3. cVolume of Comet X microreactor = 2.4 mL.
  4. dVolume of β-type microreactor = 2.7 mL.
  5. eVolume of T-shaped microreactor = 1.6 mL.
  6. fIsolated yield.
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