Table 1. Enantiomerization Barriers of TACN Tri(thio)urea Derivatives 1a–g and 2a,b with a Cyclic Hydrogen-Bonding Network^a.

entry	compound	X	R	solvent	ΔG‡25°C (kJ mol–1)
1	1a	O	4 MeOC6H4	d2-TCE	63.2
2	1a	O	4-MeOC6H4	d8-toluene	65.3
3	1b	O	4-ClC6H4	d8-toluene	63.2
4	1c	O	4-(CO2Et)C6H4	d8-toluene	65.1
5	1d	O	3,5-bis(CF3)C6H3	d8-toluene	67.5
6	1d	O	3,5-bis(CF3)C6H3	d2-TCE	70.0
7	1e	O	3,5-bis(Me)C6H3	d2-TCE	64.4
8	1f	O	4-pyridyl	d2-TCE	64.5
9	1g	O	n-Bu	CDCl3	49.0
10	2a	S	4-MeOC6H4	d2-TCE	62.4
11	2b	S	3,5-bis(CF3)C6H3	d2-TCE	70.5

^aSpectral simulations were performed assuming all four diastereotopic TACN protons exchange at the same rate. d₂-TCE = d₂-tetrachloroethane.