Table 3.

PBu₃-Catalyzed [3 + 2] Cycloadditions of Azomethine Imines 1 with the Allenoate 2a^a

entry	R	time (h)	product	yield (%)b
1	Ph (1b)	24	3ba	97
2	4-MeC6H4 (1c)	24	3ca	85
3	4-i-PrC6H4 (1d)	24	3da	89
4	4-OMeC6H4 (1e)	30	3ea	77
5	4-FC6H4 (1f)	24	3fa	91
6	4-ClC6H4 (1g)	20	3ga	93
7	4-BrC6H4 (1h)	20	3ha	97
8	4-CNC6H4 (1i)	12	3ia	87
9	4-CF3C6H4 (1j)	24	3ja	98
10	3-NO2C6H4 (1k)	24	3ka	97
11	2-NO2C6H4 (1l)	24	3la	94
12c	2-MeC6H4 (1m)	48	3ma	70
13c	2-PhC6H4 (1n)	48	3na	50
14c	1-naphthyl (1o)	48	3oa	57
15	2-naphthyl (1p)	24	3pa	96
16	4-pyridyl (1q)	20	3qa	86
17	2-furanyl (1r)	20	3ra	99
18	cyclohexyl (1s)	36	3sa	55
19	n-Bu (1t)	72	3ta	41
20	i-Pr (1u)	72	3ua	48

^a1.2 equiv of allenoate was used.

^bIsolated yield.

^cThe reaction was run at 40 °C.