Table 1 The optimization of reaction conditionsa.

From: Intermolecular diastereoselective annulation of azaarenes into fused N-heterocycles by Ru(II) reductive catalysis

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Entry

Catalyst

Base

P1 (%)b

A1″ (%)b

1

[Ru(p-cymene)Cl2]2

K2CO3

<10

8

2

[Ru(p-cymene)Cl2]2

t-BuOK

< 10

42

3

[Ru(p-cymene)Cl2]2

Mg(OMe)2

90

0

4

[Ru(p-cymene)Cl2]2

MeOK

< 10

53

5

-

Mg(OMe)2

0

0

6

[Ru(p-cymene)Cl2]2

–

0

0

7

[Cp*IrCl2]2

Mg(OMe)2

85

trace

8

[IrCl(COD)]2

Mg(OMe)2

74

trace

9

[Ru(p-cymene)Cl2]2

Mg(OMe)2

(0, 0, 61)c

(0, 0, 0)c

10

[Ru(p-cymene)Cl2]2

Mg(OMe)2

(58, 91, 86)d

(0, 0, 0)d

11

[Ru(p-cymene)Cl2]2

Mg(OMe)2

(33, 25)e

(0, 0)e

12

[Ru(p-cymene)Cl2]2

Mg(OMe)2

(42, 30)f

(0, 0)f

  1. Cp*: 1,2,3,4,5-pentamethylcyclopentadiene, cod: 1,5-cyclooctadiene, DMF: N,N-dimethylformamide.
  2. aUnless otherwise stated, the reaction in MeOH (1 mL) was performed with A1 (0.2 mmol), B1 (0.2 mmol), cat. (1 mol%), base (0.75 eq), (CH2O)n (10 eq) at 65 °C for 18 h under N2 protection.
  3. bNMR yield by using anisole as the internal standard.
  4. cYields are with respect to the use of DMF, 1,4-dioxane, ethanol as the solvent, respectively.
  5. dYields are with respect to the temperature at 45 °C, 55 °C, 75 °C, respectively.
  6. eYields are with respect to 0.5 and 0.3 eq of Mg(OMe)2, respectively.
  7. fYields are with respect to 8 and 5 eq (CH2O)n, respectively.
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