Synthesis of (1E,3E)-1,4-diarylbuta-1,3-dienes promoted by μ-OMs palladium–dimer complex

BMC Chemistry

Table 1 Optimization for the reaction condition

Entry	Catalyst/5%	Solvent	Base	T/°C	t/h	Yield/%^a
1	Pd(OAc)₂	Toluene	K₂CO₃	80	36	19
2	Pd₂(dba)₃	Toluene	K₂CO₃	80	24	11
3	Pd(OAcCF₃)₂	Toluene	K₂CO₃	80	24	15
4	μ-OMs dimer	Toluene	K₂CO₃	80	36	51
5^b	μ-OMs dimer/PPh₃	Toluene	K₂CO₃	80	24	Trace
6	Pd-Xphos	Toluene	K₂CO₃	80	24	Mix
7	μ-OMs dimer	Toluene	K₂CO₃	120	18	74
8	μ-OMs dimer	DMF	K₂CO₃	120	12	52
9	μ-OMs dimer	CH₃CN	K₂CO₃	120	12	21
10	μ-OMs dimer	NMP	K₂CO₃	120	12	50
11	μ-OMs dimer	DMSO	K₂CO₃	120	12	48
12	μ-OMs dimer	Toluene	Li₂CO₃	120	24	mix
13	μ-OMs dimer	Toluene	Cs₂CO₃	120	15	68
14	μ-OMs dimer	Toluene	K₃PO₄	120	20	62
15	μ-OMs dimer	Toluene	Et₃N	120	18	70
16^c	μ-OMs dimer	Toluene	K₂CO₃	120	24	65

Reactions were carried under Ar in Schlenk flasks. 1a (0.5 mmol), 2a (0.5 mmol), Pd* (5 mol%), solvent (2 mL), base (2.0 equiv.), 80–120 °C
^aIsolated yields
^bReaction condition: μ-OMs dimer (0.01 mmol)/PPh₃ (0.011 mol) was stirred at room temperature in DCM (1 mL) under Ar for 0.5 h, then 1a (0.5 mmol), 2a (0.5 mmol), toluene (2 mL), K₂CO₃ (2.0 equiv.) were added and stirred at 80 °C
^cThe catalyst loading is 2.5 mol%

ISSN: 2661-801X