49785-67-3Relevant academic research and scientific papers
Cobalt-mediated [2+2+2] cycloadditions of pyrimidine derivatives to alkynes
Pelissier, Helene,Rodriguez, Jean,Vollhardt, K. Peter C.
, p. 3549 - 3561 (2007/10/03)
The scope and limitations of the cobalt-mediated [2+2+2] cycloaddition of pyrimidine derivatives to alkynes has been investigated. The 5,6-double bond of these heterocyclic nuclei has been found to participate in an entirely intermolecular fashion to generate chemo- and stereoselectively novel, fused and substituted 5,6-dihydropyrimidine cobalt complexes, which upon oxidative demetallation liberate the corresponding new heterocyclic ligand. On the other hand, 1-alkynyl pyrimidines have been found to be suitable partners in the cocyclization with disubstituted alkynes, such as bis(trimethylsilyl)acetylene (BTMSA) or dimethyl 2-butyn-1,4-dioate (DMAD), to allow the direct preparation of hitherto unknown dihydropyrido[3,2-ij]quinazoline cobalt complexes. Effects of the substitution on the pyrimidine nucleus, the cocyclization partner, the complex auxiliary, and the reaction conditions were examined, and in some cases competing pathways that lead to [CpCo(cyclobutadienes)], cyclopentadienone complexes, and compounds that arise from a C-H activation-type reaction were observed.
