“Organic mechanosynthesis” involves chemical, organic
transformations by applying mechanical energy to form consciously desired
products. In this book chapter, such products are 4-methyl-2H-chromen-2-ones
(4-methylcoumarin molecules), including 7-amino-4-methyl-2H-chromen-2-one (7-amino-4-methylcoumarin,
coumarin 120), an important molecule and building block in biophysical research
as a common fluorescent probe. The Pechmann condensation is one of the most
straightforward methods for preparing substituted 4-methyl-2H-chromen-2-ones
using a wide spectrum of reaction parameters, which generally suffer from harsh
reaction conditions, e.g., stoichiometric amounts of strong acids or bases, no
reusability of catalyst, production of large acidic wastes, elevated
temperature, and prolonged reaction time. Considering the significance of green
and sustainable protocols for obtaining such chromenone molecules, the
mechanochemical Pechmann procedures allow for avoiding the use of such harsh
reaction conditions This book chapter describes a simple and efficient method
for the preparation of 4-methyl-2H-chromen-2-ones series through the
acid-catalyzed Pechmann condensation under a rapid and environment-friendly
protocol using a high-speed ball mill mixer at room temperature with short
reaction times under solvent-free conditions. Substituted 4-methylcoumarins
derived from phenols (or naphthols) and ethyl acetoacetate in the presence of 3
mol% InCl3 were obtained in good yields (52-95%).
Author(s) Details:
Vladimir V. Kouznetsov,
Laboratorio de Química Orgánica y Biomolecular, Universidad
Industrial de Santander, Bucaramanga, Colombia.
Please see the link here: https://stm.bookpi.org/RDCBR-V2/article/view/14256
