Table 2. Solvent Screening with (HO)P(OEt)₂A^a.

entry	solvent	1a (%)b	3aa (%)b	4aa (%)b
1	cumene	9	84	<5
2	toluene	9	85	<5
3	dioxane	14	77	<5
4	2-Me-THF	18	74	<5
5	benzonitrile	<5	46	7
6	iPrOH	>95	no reaction	no reaction

^aReaction conditions: 1a (0.5 mmol) and 2a (1.5 equiv) in technical solvent (0.5 mL).

^b1H NMR yields/recoveries are the average of two independent experiments and were determined with respect to 1,3,5-trimethoxybenzene as internal standard.