Funayama S, Cordell G A
J Nat Prod. 1985 Nov-Dec;48(6):938-43. doi: 10.1021/np50042a009.
The rearrangement of dihydronoracronycine (3) to dihydroisonoracronycine (4) proceeds by way of an intermolecular reaction rather than an intramolecular reaction as had originally been supposed. Deuterium-labeling studies showed the incorporation of deuterium at C3, C12, and the geminal methyl positions of dihydroisonoracronycine (4). Because no reaction occurred when the bisnor derivative was treated in the same manner as 3, it appears that the chromene geminal methyl groups are important for the rearrangement to occur.
二氢降降钩吻素子（3）重排为二氢异降钩吻素子（4）的过程是通过分子间反应进行的，而不是像最初所认为的那样通过分子内反应。氘标记研究表明，氘掺入到了二氢异降钩吻素子（4）的C3、C12以及偕二甲基位置。由于当双降衍生物以与3相同的方式处理时没有发生反应，所以看来色烯偕二甲基对于重排的发生很重要。
