Table 1.

Asymmetric Cyclopropanation of Styrene with Tosylhydrazones by Metalloradical Catalysts [Co(D₂-Por*)]^a

entry	R	catalyst	product	yield (%)b	dec	ee (%)d
1	H (1a)		3aa	46	88:12	-
2	H (1a)		3aa	64	89:11	−42
3	H (1a)		3aa	65	78:22	<5
4	H (1a)		3aa	67	95:5	26
5	2-MeO (1b)		3ba	78	95:5	99
6	2-Et (1c)		3ca	87	85:15	33
7	4-MeO (1d)		3da	23	93:7	23
8	3-MeO (1e)		3ea	69	95:5	23

^aCarried out with 1x (0.1 mmol) and 2a (1.5 equiv.) in the presence of Cs₂CO₃ (2 equiv.) in methanol (0.6 mL).

^bIsolated yields.

^cDetermined by ¹H NMR.

^dDetermined by chiral HPLC for the major trans diastereomer.