Overall barriers (ΔG^‡) and reaction energies (ΔG_C and Δ_rG) for the nucleophilic thiol addition^a.

Substrate			ΔG‡	ΔGC	ΔrG
Vinyl-	X = S	10	27.34	20.82	−6.96
Ethynyl-		13-E b	29.67c	7.69	−21.15
		13	24.67	11.79	−19.63
	X = O	14	26.89	14.96	−20.56
	X = NH	15	30.20	19.98	−17.61

^aEnergies in kcal mol⁻¹.

^bReaction pathway that affords an E-isomer was evaluated.

^cThe barrier is an estimate obtained from the transition state calculation with the constrained geometry of P–C–C–S group (see ESI 5.7 for details).