Table 2. Enantioselective Nazarov cyclization of 2 cooperatively catalyzed by ZnCl₂ and (R)-1e: influence of N-protecting groups ^a .

Entry	R2	Product	Yield b (%)	er c
1	Me (2a)	3a	98	91 : 9
2	iPr (2b)	3b	98	90 : 10
3	Allyl (2c)	3c	93	89 : 11
4	Bn (2d)	3d	87	88 : 12
5	Ph (2e)	3e	90	92 : 8
6	An (2f)	3f	95	92 : 8
7	4-CF3C6H4 (2g)	3g	76	91 : 9
8	2-Np (2h)	3h	92	92 :  8

^aReaction conditions: ZnCl₂/(R)-1e/2 = 0.01 : 0.012 : 0.2 (mmol) in 3 mL DCE, 40 °C, 48 h.

^bIsolated yield.

^cDetermined by HPLC using a Chiralpak AD-3 or Chiralcel OD-3 column.