Activation energies (ΔG^‡, kcal mol⁻¹) using M06-2X/6-31+G(d) for electrocyclic ring-closure of variously functionalised 3,Z-disubstituted (Z = 4–6) octatetraenes.

			R2
			CH3	NH2	OH	F	C(O)H	CN	NO2
	R1	CH3	19.2	20.0	18.7	16.6	17.2	18.5	16.4
		NH2	19.3	17.3	18.5	17.1	17.5	19.7	22.1
		OH	17.6	19.3	18.8	16.6	16.4	17.0	15.4
		F	16.8	18.4	17.6	16.0	15.1	15.9	14.7
		C(O)H	16.0	17.8	16.3	13.9	11.8	13.9	11.9
		CN	18.7	21.1	18.9	17.1	14.3	16.5	14.9
		NO2	16.3	22.8	10.1	15.0	13.0	15.2	12.1
	R1	CH3	17.2	19.2	19.1	16.8	16.2	17.1	16.2
		NH2	17.5	20.8	19.0	16.7	16.6	18.0	16.5
		OH	16.8	17.6	18.5	16.4	15.3	17.6	16.2
		F	16.6	17.8	17.2	15.7	14.4	17.1	15.2
		C(O)H	14.5	16.1	13.7	11.8	11.9	12.8	10.6
		CN	16.3	18.0	18.3	16.3	14.7	15.5	14.8
		NO2	12.8	13.1	14.3	9.8	10.7	12.8	10.4
	R1	CH3	18.4	19.9	20.0	18.7	16.1	18.4	15.5
		NH2		20.8	19.7	19.1	15.9	19.5	16.5
		OH			19.4	18.0	14.8	18.1	14.5
		F				17.6	14.3	17.1	12.5
		C(O)H					12.0	15.0	9.3
		CN						17.5	14.0
		NO2							9.5