Table 2.

Enantioselective copper-catalyzed conjugate addition of Grignard reagents to cyclohexenone ( 8 )

graphic
Entry* RMgBr Ligand Regio, % ee 9, % 9 Conf, R/S
1§ EtMgBr 1 95 [69] 96 9a (+)-R
2 EtMgBr 2 80 10 9a (+)-R
3 EtMgBr 3 96 94 9a (+)-R
4 EtMgBr 4 92 93 9a (+)-R
5 EtMgBr 5 69 45 9a (+)-R
6 EtMgBr 5 89 40 9a (+)-R
7 EtMgBr 6 99 56 9a (-)-S
8* EtMgBr 6 93 30 9a (-)-S
9 MeMgBr 1 83 90 9b n.d.
10 PrMgBr 1 81 94 9c n.d.
11 BuMgBr 1 88 96 9d n.d.
12§ i-PrMgBr 1 78 [72] 1 9e n.d.
13§ i-BuMgBr 1 62 [70] 33 9f (+)
14§ graphic 1 76 [75] 95 9g (+)
15 graphic 1 80 77 9h (+)-S
16 4-Cl-BuMgBr 1 79 85 9i n.d.
17 i-PrMgBr 6 99 54 9e n.d.
18 i-BuMgBr 6 99 92 9f (-)
19 PhMgBr 6 50 40 9j n.d.
  • Conf, absolute configuration; n.d., not determined.

  • * More than 98% conversion after 15 min at 0°C using CuCl.

  • Regioselectivity [9/(9 + 10)] × 100.

  • Absolute configuration and/or sign of optical rotation.

  • § Isolated yields are given in brackets.

  • More than 98% conversion after 2 h at -60°C using CuCl.

  • More than 98% conversion after 2 h at -60°C using CuBr·SMe2.