Table 3.

Synthesis of indanones via Nazarov cyclization

#	Starting material	Conditions	Product	Yield; dr (trans:cis)
1		5 mol % Cu(OTf)2, DCE, 60 °C		81%; >20:1
2		5 mol % Cu(ClO4)2, DCE, 45 °C		75%; >20:1
3		5 mol % Cu(ClO4)2, DCE, rt		--a; 3:1
4		cat. Sc(OTf)3/ Li(ClO4), DCE, 45 °C		81%; 3:1
5		cat. Sc(OTf)3/ Li(ClO4), DCE, 45 °C		-b
6	16d	(TMS)NTf2	18d	-b
7	16d	1.1 eq. AlCl3, DCE, 0 °C	18d	71%; 3.6:1
8	16d	1.1 eq. Sc(OTf)3, DCE, rt	18d	46%; 3.6:1
9		1.1 eq. AlCl3, DCE, 0 °C	18d	~70–75%; 3.6:1

^aSee Experimental section

^bDecomposition