Table 1 Optimization of the transition metal-catalyzed C(CO)−C bonds insertion reaction (reaction conditions: 1a (0.2 mmol), 2a (0.1 mmol), catalyst, and additive (50 mg) in DMF (0.5 mL) at room temperature under air atmosphere for 12 h).

From: Rhodium(II)-catalyzed multicomponent assembly of α,α,α-trisubstituted esters via formal insertion of O–C(sp3)–C(sp2) into C–C bonds

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Entry

Catalyst (x mol %)

Additive

Yield (%)a

1

[RuCl2(p-cymene)]2 (5)

—

51

2

Rh2(OAc)4 (2)

—

65

3

AgOAc (10)

—

60

4

Pd(OAc)2 (10)

—

0

5

Cu(OAc)2 (10)

—

0

6

[RhCp*Cl2]2 (2)

—

24

7

[Rh(cod)Cl]2 (2)

—

Trace

8

Rh2(esp)2 (2)

—

62

9

—

—

0

10

Rh2(OAc)4 (2)

4 Å MS

85

11b

Rh2(OAc)4 (2)

4 Å MS

70

12c

Rh2(OAc)4 (2)

4 Å MS

81

13

Rh2(OAc)4 (1)

4 Å MS

67

14

Rh2(OAc)4 (5)

4 Å MS

84

15d

Rh2(OAc)4 (2)

4 Å MS

80

16e

Rh2(OAc)4 (2)

4 Å MS

84

  1. aIsolated yields based on 2a.
  2. b4 Å MS (25 mg) was used.
  3. c4 Å MS (75 mg) was used.
  4. d1 mL of DMF was used.
  5. eReaction was carried out under nitrogen atmosphere. esp: α,α,α′,α′-Tetramethyl-1,3-benzenedipropionic acid.
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