Table 1.

Optimization of thioamide synthesis by reacting nitroalkanes with various sulfur sources^a

Entry	S source	Base	Yield (%)b
1	S8	K2CO3	37
2	S8	Na2CO3	24
3	S8	Cs2CO3	28
4	S8	Na2S	98
5	S8	Et3N	16
6	S8	DBU	<5
7	S8	pyridine	<5
8	S8	no base	12
9	3a	Na2S	62
10	3b	Na2S	<5
11	3c	Na2S	50
12	3d	Na2S	70

THF tetrahydrofuran, DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene.

^aReaction conditions: Nitroalkane 1a (0.2 mmol), amine 2a (0.4 mmol), S source (0.4 mmol), base (0.4 mmol) in THF (2 mL, 0.1 M).

^bIsolated yield.