Preparation of <sup>13</sup>C<sub>4</sub>-6-Methyl Anthranilic Ester via a Diels−Alder-Type Process. An Experimental and Theoretical Study to Characterize an Unexpected Isotope Exchange
作者:J. Lorenzo Alonso-Gómez、Yolanda Pazos、Armando Navarro-Vázquez、Johan Lugtenburg、M. Magdalena Cid
DOI:10.1021/ol051433f
日期:2005.8.1
through a Diels-Alder cycloaddition. Besides the expected Diels-Alder adduct 3a, the aniline 3b was also obtained in a ratio of 91:9. The observed (13)C exchange is explained on the basis of a reversible [2 + 2] cycloadditioncompeting with the [4 + 2] process. This is supported by B3LYP DFT computations, as a stepwise pathway lies very close in energy to the [4 + 2] concerted one. [reaction: see text]