Accelerations in the Lactonization of Trimethyl Lock Systems Are due to Proximity Orientation and not to Strain Effects

Table 1

AM1 and MM2 calculated thermodynamic properties of hydroxyhydrocinnamic acid derivatives. (All values were calculated by AM1 method except for the values of Es which were calculated by MM2 method.)

Structure	ΔΔ𝐇𝑓3,1	𝐓𝚫𝐒𝟑,𝟏	𝚫𝐄𝐬𝟑,𝟏	ΔΔ𝐆3,1	log𝐤^𝑏exp
PAA ^a	−1.95	−4.82	14.27	2.87	−10.000
1a	−5.25	−3.96	10.54	−1.29	−5.226
1b	−4.82	−1.77	9.95	−3.05	−5.206
1c	−12.10	−1.08	3.49	−11.03	5.771
1d	−9.39	−1.77	7.35	−7.62	−1.581

^aPAA Stands for the bimolecular reaction of phenol and acetic acid.
^bTaken from reference [10–12]. The numbers 1 and 3 refer to structures 1 and 3 (see Figure 1).