Optimization of the reaction conditions for the preparation of 1,1′-[(1R,4R)-cyclohexane-1,4-diyl]bis(3-benzylthiourea) 3a^a.

Entry	Solvent	Method	Time (min)	Yield (%)b
1	MeCN	Stirring	120	45
2	MeCN	Stirring	120	58c
3	MeCN	US	5	92
4	DCM	US	5	88
5	EtOH	US	5	21
6	H2O	US	10	25
7	Acetone	US	5	15
8	—	US	5	97
9	—	US	3	82

^aThe reaction was conducted with 1a (1.0 mmol) and 2a (0.5 mmol).

^bIsolated yields.

^cThe reaction was conducted with 1a (1.5 mmol) and 2a (0.5 mmol).