Uncovering the mechanism leading to the synthesis of symmetric and asymmetric Tröger's bases

LANZA, PRISCILA AILÍN; DUSSO, DIEGO; RAMIREZ, CRISTINA LUJÁN; PARISE, ALEJANDRO RUBÉN; MOYANO, ELIZABETH LAURA; VERA, D. MARIANO A.

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Año: 2019

1434-193X

röger´s bases have been attracting great interest due to their potential applications innanoelectronics, supramolecular chemistry, molecular recognition, biological activityand auxiliaries for asymmetric synthesis. However, a detailed step by step proposal forthe mechanism leading to the production of these compounds is still uncovered. A setof five model syntheses of symmetric and asymmetric Tröger´s base derivativesstarting from substituted anilines and formaldehyde was done and envisaged asrepresentative for understanding the underlying mechanism. All reasonable pathwayswere thoroughly scanned by means of DFT calculations. The highest energy TS wasassociated with the entrance of the first formaldehyde which produces the first out ofthree key carbocations. The last step, the closure of the methylene-bridged diazocyneheterocycle was also found of kinetic relevance and as a source of stableintermediates or byproducts. The whole mechanistic picture would provide keys for therational planning of the synthesis of these compounds.