Table 1 Condition optimizationa

From: Sila-spirocyclization involving unstrained C(sp3)−Si bond cleavage

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Entry

Variations from the “standard” conditions

Yield of 2aa [%]b

Yield of 3aa [%]b

1

None

93 (90)

trace

2

No Pd

N.R.

N.R.

3

No LiOtBu

N.R.

N.R.

4

No CuTc

67

28

5

No AgOAc

20

10

6

AgOAc (1.5 eq)

75

12

7

KOAc instead of AgOAc

85(86)

trace

8

Ag2CO3 instead of AgOAc

20

trace

9

[Pd(allyl)Cl]2 instead of [Pd]-1

N.R.

N.R.

10

Pd(PtBu3)2 instead of [Pd]-1

70(66)

19

11

Toluene instead of cyclohexane

70

12

12

2.5 mol% [Pd]-1

45

<10

13

100 °C instead of 125 °C

60

22

  1. aReactions were carried out by using [Pd]-1 (5 mol%), TcCu (20 mol%), AgOAc (2 eq), LiOtBu (3 eq) and 1aa (0.2 mmol) in cyclohexane (0.4 M) at 125 °C for 12 h. N.R. No Reaction. bYield of 2aa and 3aa, as determined by GC analysis of the mixture; the values in parentheses indicate the isolated yield.
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