. Author manuscript; available in PMC: 2015 Nov 14.

Published in final edited form as: Org Biomol Chem. 2014 Nov 14;12(42):8442–8452. doi: 10.1039/c4ob01040j

Table 1.

Hetero-Diels-Alder Type Dimerization of 3 under Different Reaction Conditions

Entry	Solvent	Temperature (°C)	Time (days)	Yield (%)^a
1	None	−20	21	68
2	None	rt	21	72
3	None	80	2	80
4	1,4-dioxane^b	rt	30	35
5	1,4-dioxane^b	110	4	70

Isolated yields.

The concentration is 0.5 mol/L