Table 3. Optimization Data for the Synthesis of 1,4-Thiazines^a.

entry	catalyst	solvent	T (°C)	yieldb (%)
1	Cu(OAc)2	CH3CN	70	45
2	CuCl	CH3CN	70	55
3	CuBr	CH3CN	70	51
4	CuI	CH3CN	70	58
5	CuI	toluene	70	trace
6	CuI	dioxane	70	53
7	CuI	DMF	70	70
8	CuI	DMSO	70	73
9	CuI	DCE	70	nr
10	CuI	H2O	70	trace
11	CuI	EL	70	40
12	CuI	DMSO	80	68
13	CuI	DMSO	60	65
14c	CuI	DMSO	70	41
15	NiCl2	DMSO	70	35
16d	FeCl3	DMSO	70

^aGeneral conditions: 1a (0.2 mmol), 2 (0.2 mmol), and copper catalyst (0.3 equiv) in 2 mL of solvent stirred for 12 h.

^bYield of the isolated product.

^cThe loading of CuI was 0.1 equiv.

^dNo expected product was observed.