Table 2. Optimization of Amine Additives^a.

entry	amine	er
1	Et3N	50.5:49.5b
2	iPr2NH	50:50c
3	PhNH2	70.5:29.5
4	PhNHiPr (4a)	74:26
5	Ph2NH	72:28
6	Ph3N	70.5:29.5
7	pyridine (C5H5N)	72:28
8	2,6-Me2-C5H3N	69:31
9	2,6-tBu2-C5H3N	73:27
10	2,6-Ph2-C5H3N	71.5:28.5
11d	4a	72:28
12e	4a	73:27
13f	no amine additive	70.5:29.5

^aFull conversion for all entries, except for entries 1 and 2.

^b36% yield.

^c52% yield.

^d1.25 mol % amine 4a was added.

^e5 mol % amine 4a was added.

^fSame as Table 1, entry 18.