Autotandem Catalysis: Inexpensive and Green Access to Functionalized Ketones by Intermolecular Iron‐Catalyzed Amidoalkynylation/Hydration Cascade Reaction via N‐Acyliminium Ion Chemistry

Abstract

Iron-based catalysts were applied in cascade-type reactions for the synthesis of different carbonyl compounds. The reactions proceeded by a new iron-catalyzed cascade of alkynylation/hydration by using both the σand π-Lewis acid properties of iron salts. The alkynylation reactions of several endo and exocyclic acetoxylactams were achieved with three different catalysts including FeCl 3 • 6H 2 O, FeCl 3 , and Fe(OTf) 3 showing the efficiency of σ-Lewis acidity of iron (III) salts in catalyzing the alkynylation reaction. We also demonstrated that the reaction sequence could be shortened by the direct use of hydroxylactams, leading to an environmentally friendly protocol, avoiding the need to perform unnecessary lengthy steps. A combination of the hard/soft iron Lewis acid properties was then used to implement an unprecedented tandem intermolecular alkynylation/intramolecular hydration sequence allowing expedient access to a new carbonyl structures from trivial materials.

Metal‐ and Catalyst‐Free Synthesis of 2‐Substituted‐Phthalimides Using 2‐(Arenesulfonyl)Phthalimide as Key Reagents

“…Melting points are General procedure for the preparation of N-substituted arenesulonyl phthalimides (3) and arenesulfonyl succinimide (5): Prepared by modification of reported methodology. [18,21,24,25,29] In a dry flask, a mixture of arenensulfonyl chloride (1 equiv., 30.98 mmol,)…”

“…General procedure for the preparation of N ‐substituted arenesulonyl phthalimides (3) and arenesulfonyl succinimide (5) : Prepared by modification of reported methodology [18,21,24,25,29] . In a dry flask, a mixture of arenensulfonyl chloride (1 equiv., 30.98 mmol,) and imide (1.1 Equiv., 33.98 mmol,) in acetonitrile (150 mL) was cooled to 0 °C in an ice bath for 30 min under nitrogen.…”

“…Although the synthesis of arenesulfonyl phthalimide derivatives from phthalimide and the corresponding arenesulfonyl chloride is easy, [18,19] only a few studies are found to explore the chemical scope of arenesulfonyl phthalimide compounds. [20][21][22][23] Kurtuk and Ozturk studied the reaction of arenesulfonyl phthalimides with amines and proposed the formation of a product, though its characterization was not reported. [24] In the current study, we report that arensulfonylphthalimides are excellent reagents for easy access to 2-substituted phthalimides.…”