NMR IN ANISOTROPIC MEDIA IN THE IDENTIFICATION OF NEW DOMINO REACTIONS

MISCHNE, M. P.; RIVEIRA, M. J.; GIL, R. R.; NAVARRO-VÁZQUEZ, A.

Santa Fe

Workshop; III WORKSHOP ON MAGNETIC RESONANCE NMR AND EPR AT THE FOREFRONT OF RESEARCH; 2016

Depto. de Física, Fac. de Bioq. y Cs. Biol. de la UNL

Domino reactions are powerful synthetic tools for the construction of polycyclic scaffolds.1 Essentially, these involve two or more bond-forming or ?breaking transformations that take place under the same reaction conditions, without any further addition of reagents and/or catalysts, and in which each step results as a consequence of the functionality formed in the previous one without any isolation of intermediates. Resembling Nature as regards synthetic efficiency, these processes are arguably highly attractive to pharmaceutical and materials chemistry. Taking into account that after such combination of multiple reactions the structure of products may hardly resemble those of starting materials, accurate and fast structural elucidation is critical for the prompt identification and development of new domino processes. In this regard, our studies on the reactiviy of unsaturated carbonyl compounds led to the accidental discovery of two domino reactions: the condensationbetween dienals and 1,3-dicarbonyl substrates for the synthesis of cyclopenta[b]furans and the photooxygenation of 2H-pyrans for the synthesis of spirocyclic ketones (Figure).2,3 Remarkably, both the constitution and configuration of such unexpected products were firmly established by means of residual dipolar coupling analysis.Figure: New domino reactions based on Knoevenagel condensationsREFERENCES1. Tietze, L. F.; Brasche, G.; Gericke, K. M., ?Domino reactions in organic synthesis?,Wiley-VCH, 2006, Weinheim, Germany.2. Riveira, M. J.; Gayathri, C.; Navarro-Vázquez, A.; Tsarevsky, N. V.; Gil, R. R.; Mischne,M. P. Org. Biomol. Chem. 2011, 9, 3170-3175.3. Riveira, M. J.; Trigo-Mouriño, P.; Troche-Pesqueira, E.; Martin, G. E.; Navarro-Vázquez,A.; Mischne, M. P.; Gil, R. R. J. Org. Chem. 2015, 80, 7396-7402.