Table 1 Optimization of the reaction conditionsa.

From: Silver/chiral pyrrolidinopyridine relay catalytic cycloisomerization/(2 + 3) cycloadditions of enynamides to asymmetrically synthesize bispirocyclopentenes as PDE1B inhibitors

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Entry

M

C

Yield (%)

Er

1

PPh3AuCl, AgSbF6

PPh3

N.R.

–

2

PPh3AuCl, AgSbF6

DABCO

N.R.

–

3

PPh3AuCl, AgSbF6

C1

49

76:24

4

AgOTf

C1

66

79:21

5

Ag2CO3

C1

56

72:28

6

AgOAc

C1

58

80:20

7

AgOAc

C2

26

74:26

8

AgOAc

C3

42

70:30

9

AgOAc

C4

37

56:43

10

AgOAc

C5

66

74:26

11

AgOAc

C6

22

83:17

12

AgOAc

C7

52

85:15

13

AgOAc

C8

86

86:14

14

AgOAc

C9

82

89:11

15b

AgOAc

C9

80

95:5

  1. aConditions: 1a (0.1 mmol) and M (10 mol%) in CHCl3 (1.0 mL) was stirred at 40 °C for 1 h before 2a (0.1 mmol) and C (20 mol%) was added. Then, the mixture was stirred for 8 h.
  2. bAfter 2a and C9 were added, the reaction was stirred at 0 °C for 48 h and then at 40 °C for 3 h.
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