Optimization of the reaction parameters^a.

Entry	Deviation in conditions	3aa/4aab	3aa c (%)
1	None	99 : 1	92
2	L2 was used instead of L1	99 : 1	87
3	L3 was used instead of L1	99 : 1	35
4	L4 was used instead of L1	99 : 1	52
5	L5 was used instead of L1	25 : 1	16
6	L6 was used instead of L1	—	0
7	L7 was used instead of L1	—	>5
8	(C7H8)3Mo(CO)3 was used	99 : 1	82
9	THF was used as solvent	—	>5
10	Toluene was used as solvent	—	>5
11	DCE was used as solvent	25 : 1	35
12	iPrOH was used as solvent	99 : 1	77
13	THF/EtOH (5 : 1) as solvent	25 : 1	25
14	DCE/EtOH (5 : 1) as solvent	25 : 1	63
15	Without Mo or L1	—	0

^aReaction conditions: Mo-catalyst (10 mol%), ligand (15 mol%), 1a (0.2 mmol), PhSO₂Na 2a (0.3 mmol), solvent (1.0 mL, 0.2 M), 60 °C, 24 hours.

^bDetermined by ¹H-NMR of the crude reaction mixture.

^cIsolated yields.