Table 2.

Control Experiments to Probe Reaction Mechanism

Entry	Xa	Lewis Acids (Equiv.)	Solvent (0.1M)	T (oC)	t (h)	Yields (%)
						2a	3ab
1	F	B(C6F5)3 (2.2)	CH2Cl2	RT	30	85	0
2	1v (C=O)	B(C6F5)3 (2.2)	CH2Cl2	RT	30	NR	NR
3	MeO	B(C6F5)3 (2.2)	CH2Cl2	RT	30	NDc	NDc
4	Cl	B(C6F5)3 (2.2)	CH2Cl2	RT	30	NR	NR
5	Br	B(C6F5)3 (2.2)	CH2Cl2	RT	30	0	29
6	F	B(C6F5)3 (0.2)	(CF3)2CHOHd	50	2	84	0
7	1v (C=O)	B(C6F5)3 (0.2)	(CF3)2CHOHd	50	2	NR	NR
8	MeO	B(C6F5)3 (0.2)	(CF3)2CHOHd	50	2	NR	NR
9	Cl	B(C6F5)3 (0.2)	(CF3)2CHOHd	50	2	0	63
10	Cl	–	(CF3)2CHOHd	50	2	0	61
11	Br	B(C6F5)3 (0.2)	(CF3)2CHOHd	50	2	0	81
12	Br	–	(CF3)2CHOHd	50	2	0	86
13	F	B(C6F5)3 (0.2)	p-C6H4F2	reflux	24	0	87
14	MeO	B(C6F5)3 (0.2)	p-C6H4F2	reflux	24	0	0
15	Cl	B(C6F5)3 (0.2)	p-C6H4F2	reflux	24	0	Trace
16	Br	B(C6F5)3 (0.2)	p-C6H4F2	reflux	24	0	9

NR, no reaction; RT, room temperature; ND, not detected.

^aSubstrates: 1,5-diphenylpentan-3-one (1v), (3,3-dimethoxypentane-1,5-diyl)dibenzene (1w), (3,3-dichloropentane-1,5-diyl)dibenzene (1x), and (3,3-dibromopentane-1,5-diyl)dibenzene (1y).

^bNMR yields.

^cComplex mixture.

^dConcentration (0.05 M).