Activation energies (ΔG^‡, kcal mol⁻¹) using M06-2X/6-31+G(d) for electrocyclic ring-closure of variously functionalised 4,5-disubstituted octatetraenes.

		R2
		CH3	NH2	OH	F	CHO	CN	NO2
R1	CH3	25.4	23.5	21.8	15.5	22.9	20.4	23.6
	NH2		21.0	20.5	17.6	19.8	18.1	22.5
	OH			21.0	18.8	18.2	17.6	18.1
	F				15.8	16.1	16.3	18.7
	CHO					21.1	18.9	21.0
	CN						20.1	22.3
	NO2							23.5