Efficient Preparation of 2-Indolyl-1-nitroalkane Derivatives Employing Nitroalkenes as Versatile Michael Acceptors: New Practical Linear Approach to Alkyl 9<i>H</i>-β-Carboline-4-carboxylate

Abstract

The combination of cerium(III) chloride heptahydrate and sodium iodide supported on silica gel is known to promote Michael-type additions. Continuing our work on solvent-free conditions, the CeCl3.7H2O-NaI-SiO2 system catalyzes the addition of a variety of indoles and nitroalkenes, giving 2-indolyl-1-nitroalkane derivatives in good yields. Development of this method has resulted in a new protocol for the synthesis of 4-substituted beta-carbolines.