Table 1.

Palladium catalyzed cross coupling preparation of N-heterocyclic isoxazole anthryl esters, 2a–2e.

Entry	Palladium reagent	Boron reagent (Product)	Phosphine	Base	Temperature (°C) solvent	Time	Yield
1	Pd2(dba)3	4-PyrB(TMP) (2d)	(t-Bu)3P	KF	RT THF	5 d	0
2	PdL4	4-PyrB(OH)2 (2d)	Ph3P	KF	RT	72 h	0
3	PdL4	4-PyrB(OH)2 (2d)	Ph3P	KF	40	24 h	10
4	XPhos Pd G3	4-PyrB(OH)2 (2d)	XPhos	Na2CO3 (aq)	90	24 h	40
5	PdCl2(dppf)	4-PyrB(TMP) (2d)	Dppf	KOAc	CH3CN reflux	3 d	50
6	XPhos Pd G3	4-PyrB(OH)2 (2d)	XPhos	Na2CO3 (aq)	120, microwave	20 m	68
7	PdL4	3-PyrB(OH)2 (2c)	Ph3P	Na2CO3	120, microwave	1 h	81
8	XPhos Pd G3 CuOAc2	2-PyrMIDA (2b)	XPhos	K3PO4	100	24 h	20
9	XPhos Pd G3	8′-QuinB(OH)2 (2e)	XPhos	Na2CO3	40	72 h	57

Abbreviations: dba dibenzylidene acetone, dppf bisdiphenylphosphineferrocene, TMP tetramethylpicolinate, RT room temperature.