Table 1.

Catalyst and Reaction Optimization

entrya	thiourea catalyst	nucleophilic catalyst	acylating agent (X =)	yieldb (%)	eec (%)
1	3a	DMAP	OBz	19	41
2	3a	PPY	OBz	21	52
3	3a	PPY	Cl	0	-
4	3a	PPY	F	84	81
5	3b	PPY	F	88	87
6	3c	PPY	F	29	75
7	3d	PPY	F	80	92
8	4	PPY	F	9	-
9	5	PPY	F	20	<5
10d	3d	PPY	F	86	93

^aReactions run on a 0.08 mmol scale.

^bYields determined by ¹H NMR analysis relative to p-xylene as an internal standard.

^cEnantiomeric excess determined by HPLC analysis on commercial chiral columns.

^dReaction run using 5 mol% thiourea catalyst and 6 mol% PPY at −60 °C in TBME (0.01 M) for 8 h.