Table 1.

Optimization of the 1,3-dipolar cycloaddition of 6b and tert-butyl acrylate using chiral phosphoramidite ligands.

Entry	Catalysta	Base	Yieldb (%)	eec (%)
1	(Sa)-7/AgClO4	Et3N	___d	rac
2	(Sa)-7/AgSbF6	Et3N	___d	rac
3	(Sa)-7/AgTFA	Et3N	___d	rac
4	(Sa)-7/AuTFA	DIPEA	___d	___d
5	(Sa,R)-8/AgClO4	Et3N	82	20
6	(Sa,R)-8/AgSbF6	Et3N	82	99
7	(Sa,R)-8/AgTFA	Et3N	82	60
8	(Sa,R)-8/AgTFA	DIPEA	82	64
9	(Sa,R)-8/AuTFA	DIPEA	___d	___d
10	(Sa,R,R)-9/AgClO4	DIPEA	86	30
11	(Sa,R,R)-9/AgSbF6	Et3N	72	40
12	(Sa,R,R)-9/AgSbF6	DIPEA	82	40
13	(Sa,R,R)-9/AgTFA	Et3N	82	50
14	(Sa,R,R)-9/AgTFA	DIPEA	82	40
15	(Sa,R,R)-9/AuTFA	DIPEA	___d	___d
16	(Sa,R,R)-10/AgClO4	Et3N	___d	rac
17	(Sa,R,R)-10/AgTFA	Et3N	___d	rac
18	(Sa,R,R)-10/AgSbF6	Et3N	___d	rac
19	(Sa,R,R)-11/AgClO4	Et3N	72	86
20	(Sa,R,R)-11/AgSbF6	Et3N	___d	rac
21	(Sa,R,R)-11/AgTFA	Et3N	___d	rac
22	(R,R)-12/AgClO4	Et3N	79	30
23	(R,R)-12/AgTFA	Et3N	87	40
24	(R,R)-12/AgSbF6	Et3N	86	30

^aThe generation of silver catalysts was achieved by mixing equimolar amounts of silver(I) or gold(I) salt and the corresponding phosphoramidite. ^bAfter flash chromatography (silica gel). The observed endo:exo ratio was always >98:2 (¹H NMR). ^cDetermined by using analytical chiral HPLC columns (Daicel, Chiralpak AS). ^dNot determined.