Figure 5.

Kinetics of the intramolecular Diels-Alder reaction of adduct 6 in ethanol at 37 ºC. (A) Spectra collected every 1 hour, the inset shows the differential spectrum between 7 h and initial time. (B). The decay at 231 nm fit as a single exponential decay, indicating a first order reaction, with a rate constant k = (9 ± 1) × 10⁻⁵ s⁻¹ (n = 3). Absorbance at 320 nm remained constant (coumarin moiety), and was used as a normalizing element.