Entry

Diyne

R1

R²

Isolated Yield [a]

Ratio [b] 7/8

1

4a

CH₃

H

95%

33/1

2

4b

H

H

84% [c]

3/1

3

4c

n-Bu

H

71%

10/11

4

4d

TMS

H

31% [c]

1/2[d]

5

4e

Ph

H

92%

5/4

6

4f

4-Ph-Ph

H

34%

2/1

7

4g

H

Ph

68% [e]

>99/1

8

4h

H

4-MeO-Ph

36% [e]

>99/1

9

4i

H

Benzofuranyl-2

21% [e]

>99/1