. Author manuscript; available in PMC: 2010 Feb 11.

Published in final edited form as: J Am Chem Soc. 2009 Feb 11;131(5):1947–1957. doi: 10.1021/ja8079548

Table 2.

Activation Barriers and Their Dissection into Distortion and Interaction Energies for Endo and Exo TSs of 2c+A₂ (kcal/mol).

Entries	Method		ΔE^‡	ΔE_d^‡		ΔE_i^‡
Entries	Method		ΔE^‡	diene 2c	dienophile complex A₂	ΔE_i^‡
1	B3LYP/6−31G(d)	endo	−0.1	9.5	11.9	−21.4
2	B3LYP/6−31G(d)	exo	−3.0	7.9	8.8	−19.7
3	MP2/6−31+G(d)	endo	−11.4	9.8	12.0	−33.1
4	MP2/6−31+G(d)	exo	−13.5	8.3	8.8	−30.6