Optimization of the Pd–NHC–MIL-101(Cr)-catalyzed Heck reaction between aryl halides and 1,4-distylbenzene^a.

Entry	x	1a : 2a ratio	Yield 3ab	Yield 3a′b
1	1.5	1 : 2	6	85 (79)
2	1.5	2 : 1	70	20
3	1.5	1 : 2.2	5	88 (81)
4	1.5	2.2 : 1	83 (77)	2
5	1.25	1 : 2.2	6	78 (71)
6	1.25	2.2 : 1	70	8
7	2.0	1 : 2.2	4	87 (78)
8	2.0	2.2 : 1	84	20
9	1.5	1 : 2.2	20	58c
10	1.5	2.2 : 1	71	18c

^aReaction conditions: 1a (1.0 mmol), 2a (based on the ratio), Pd–NHC–MIL-101(Cr) (x mol%), DMF (5 mL), K₂CO₃ (2.5 mmol), 110 °C, 12 h.

^bNMR yield.

^cThe Pd/C was used as catalyst. The yields in parentheses related to isolated yields.