Table 2.

Ni-Catalyzed Cycloaddition of Diynes and Ketenes^a

Entry	Diyne	Ketene	Product	Yieldbc
1	1 (R′ = Me)	a Ar= Ph R=Et	1a	82%
2	1	b Ar= Ph R=Ph	1b	46%
3	1	c Ar= Ph R=i-Pr	1C	50%
4	2 (R′ = Ph)	a Ar= Ph R=Et	2a	65%
5	3 (X=C(CO2Et)2)	a Ar= Ph R=Et	3a	54%
6	4 (X=CH2)	a Ar= Ph R=Et	4a	35%
7	5	a Ar= Ph R=Et	5a	50%
8	5	d Ar= Ph R=n-Pr	5d	55%
9	6	a Ar= Ph R=Et	6a	33%
10	7	a Ar= Ph R=Et	7a	91%
11	7	e Ar= p-OMe-Ph R=Et	7e	81%
12	7	f Ar= p-Me-Ph R=Et	7f	80%
13	7	g Ar= p-F-Ph R=Et	7g	>99%c
14	7	h Ar= Ph R=Me	7h	65%
15	7	d Ar= Ph R=n-Pr	7d	76%
16	7	i	7i-i'	82%
17	7	j	7j	76%
18	8 (X=C(CO2Et)2)	a	8a	78%
19	9 (X= CH2)	a	9a	33%

^aReaction conditions: 5 mol% Ni(COD)₂, 5 mol% DPPB, diyne (1 equiv, 0.1 M), ketene (1.2 equiv) in toluene at 60 °C, 5 h.

^bIsolated yields.

^cAverage of at least two runs.

^dCrude ketene was used.