Table 1 Optimization of the reaction conditions for the synthesis of 3j.

From: Synthesis of novel aryl-substituted 2-aminopyridine derivatives by the cascade reaction of 1,1-enediamines with vinamidinium salts to develop novel anti-Alzheimer agents

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Entry

Solvent

Base

T (°C)

Time/h

Yielda (%)

1

EtOH

–

Reflux

12

–

2

CH3CN

–

Reflux

12

–

3

THF

–

Reflux

12

–

4

DMF

–

100

12

30

5

DMSO

–

100

12

45

6

DMSO

Piperidine

100

12

65

7

DMSO

K2CO3

100

12

54

8

DMSO

NaOMe

100

12

70

9

DMSO

Et3N

100

12

88

10

DMSO

Et3N

120

12

85

11

DMSO

Et3N

80

12

92

12

DMSO

Et3N

60

12

86

  1. Reaction conditions: N-(2-(4-bromophenyl)-3-(dimethylamino)-allylidene)-N-methylmethanaminium perchlorate 1d (0.5 mmol), N-(4-methoxyphenyl)-2-nitroethene-1,1-diamine 2a (0.5 mmol), base (1 eq.), solvent (1 mL), 12 h.
  2. aIsolated yield.
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