Table 3. Stereoselective 1,3-Dipolar Cycloaddition between 1a–o and 2 Catalyzed by the Second-Generation Macmillan Catalyst^a.

entry	1	solvent	catalyst	T (°C)	t (h)	conversionb%	productc (yield %)	3bS/R
1	1a	toluene	C	rt	<0.2	>99	3a (99)	97/3
2	1b	toluene	C	rt	4	>99	3b (90)	96/4
3	1c	toluene	C	rt	4	>99	3c (92)	95/5
4	1d	toluene	C	rt	4	>99	3d (90)	95/5
5	1e	toluene	C	rt	<0.2	98	3e (91)	99/1
6	1f	toluene	C	rt	<0.2	>99	3f (91)	98/2
7	1g	toluene	C	rt	<0.2	>99	3g (99)	97/3
8	1h	toluene	C	rt	2	80	3h (77)	95/5
9	1i	DCM	C	rt	4	72	3i (68)	95/5
10	1j	DCM	C	rt	4	70	3j (65)	95/5
11	1k	toluene	C	rt	<0.2	>99	3k (99)	98/2
12	1l	toluene	E	rt	5d	>99	3l (80)	92/8
13	1m	toluene	E	rt	5d	>99	3m (74)	90/10
14	1n	toluene	E	rt	<0.2	>99	3n (99)	91/9
15	1o	DCM	E	rt	18d,e	>99	3o (83)	92/8
16	1b	toluene	C	–10	8	>99	3b (92)	97/3
17	1c	toluene	C	–10	8	>99	3c (94)	97/3
18	1d	toluene	C	–10	8	>99	3d (95)	97/3
19	1h	toluene	C	–10	18	97	3h (95)	97/3
20	1i	toluene	C	–10	18	91	3i (85)	97/3
21	1j	toluene	C	–10	18	92	3j (89)	96/4
22	1l	toluene	E	–10	1.5	>99	3l (82)	92/8
23	1m	toluene	E	–10	4	>99	3m (75)	90/10
24	1n	toluene	E	–10	1	>99	3n (99)	93/7
25	1o	DMC	E	–10	15	>99	3o (85)	92/8

^aAll reactions were carried out with 1.2 equiv of 2, 0.5 M concentration, and 10 mol % catalyst; complete screening is reported in Supporting Information.

^bDetermined by HPLC.

^cIsolated yields.

^dThe nitrone 1 (0.5 mmol) was added dropwise as 2 M solution within the reported reaction time.

^eThe reaction was carried out on the 5 mmol scale.