Table 2. Optimization of Conditions for the Formation of 10a and 20a(13).

no.	anhydride	solvent	conditions	result (10a by LCMS, %)
1	7a	DMA	140 °C, 6 h
2	7a	xylene	140 °C, 6 h	73
3	7a	CHCl3	RT, 6 h	67
4	7a	MeCN	RT, 6 h	68
5	7a	DCE	80 °C, 6 h	77
6	7a	MeCN	80 °C, 6 h	54
7	7a	toluene	110 °C, 6 h	92
8	7a	DMA	110 °C, 6 h

no.	anhydride	solvent	conditions	result (20a by LCMS, %)
9	19a	xylene	140 °C, 8 h	49
10	19a	toluene	110 °C, 8 h	30