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. 2025 Mar 3;147(10):8107–8112. doi: 10.1021/jacs.4c18378

Table 1. Reaction Optimization and Control Experiments.

entrya cat. (mol %) add. (mol %) yieldb (%) e.r.c
1 4-BArF24 (10) N(nBu)4-(R)-5 (20) 37 75:25
2 4-BArF24 (10) - 60 -
3 4-OTf (10) - 19 -
4 4-OTf (10) N(nBu)4-(R)-5 (20) 19 50:50
5 - N(nBu)4-(R)-5 (20) 8 51:49
6 - H-(R)-5 (20) 12 51:49
7 - - 12 -
8 4-BArF24 (10) H-(R)-5 (20) <5 53:47
9 4-BArF24 (10) N(nBu)4-(S)-6 (20) 23 69:31
10 4-BArF24 (10) N(nBu)4-(S)-7 (20) 35 76:24
11 4-BArF24 (10) N(nBu)4-(S)-8 (20) 46 86:14
12 4-BArF24 (10) N(nBu)4-(S)-9 (20) 69 85:15
13 4-BArF24 (10) N(nBu)4-(S)-9 (10) 34 48:52
14 4-BArF24 (10) N(nBu)4-(S)-9 (30) 54 82:18
15 - Na-(S)-9 (20) 25 49:51
16 4-(S)-9 (10) - >95 88:12
17d 4-(S)-9 (10) - >95 89:11
18d,e 4-(S)-8 (10) - 94f 93:7
19g,h 4-(S)-8 (10) - 56f 94.5:5.5
20g 4-(S)-8 (5) - 32 93.5:6.5
21g 4-(S)-8 (2) - 10 87:13
22d - H-(S)-8 (20) 9 51:49
23d - - 9 -
a

Reactions (Scheme 1) performed at 12.5/25 μmol scale using 10 equiv of cyclopentadiene (2) and the catalyst (cat.)/additive (add.) in the given amounts in toluene (100 mM).

b

Determined for endo-3a44 via 1H NMR spectroscopy using methyl 3,5-dinitrobenzoate as internal standard.

c

Determined for endo-3a via chiral HPLC.

d

50 mM concentration.

e

50 μmol scale.

f

Isolated yield of 3a (endo:exo >100:1).

g

12.5 mM concentration.

h

50 and 100 μmol scale.