Molecular iodine catalyst promoted synthesis of chromans and 4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling

Divergent synthesis of 3,4-dihydro-2H-benzo[h]chromen-2-one and fluorenone derivatives from ortho-alkynylarylketones

Our research has led to the development of a divergent synthesis approach for the synthesis of 3,4-dihydro-2H-benzo[h]chromen-2-one 3 and fluorenone 9 derivatives using ortho-alkynylarylketones as common precursors. The synthesis of 3,4-dihydro-2H-benzo[h]chromen-2-ones 3 employed silver catalyzed ketonization to form polycarbonyl intermediates which underwent double intramolecular cyclization and decarboxylation to generate a lactone and a phenyl ring in a one-pot fashion. In addition, the same precursor could be used to prepare fluorenone derivatives 9 under acidic conditions. The reaction proceeded via the formation of indenone analogs, followed by the generation of the para-quinone methide intermediate and intramolecular cyclization to provide the corresponding products in good yields.

Molecular Iodine-Catalyzed N-Benzylic Sulfonamides C-N Bond Cleavage for the Decarboxylative Substitution of β-Keto Acids

Abstract:

A molecular iodine-catalyzed system for the decarboxylative substitution reactions of β-keto acids with N-benzylic sulfonamides via sp3 C-N bond cleavage has been disclosed. This procedure provides a series of α-functionalized ketones in good to excellent yields. Furthermore, the practicability of this method could be manifested efficiently in a gram-scale synthesis.

Revisiting applications of molecular iodine in organic synthesis

Molecular iodine contributes significantly to organic transformations in synthetic organic chemistry. It works effectively due to its mild Lewis acidic character, ability as an oxidizing agent, good moisture stability, and easy availability.

Functionalization of diazotetronic acid and application in a stereoselective modular synthesis of pulvinone, aspulvinones A–E, G, Q and their analogues

Diastereoselective aldol condensation of diazotetronic acid and a subsequent arene C–H insertion provides an efficient route to the aspulvinone motif.

Synthesis of 4-aryl-1-ethyl-7-methyl-1,9-dihydropyrano[4,3-b]pyrazolo[4,3-e] pyridin-5(4H)-one via a three-component condensation

An efficient synthesis of a series of 4-aryl-1-ethyl-7-methyl-1,9-dihydropyrano[4,3- b]pyrazolo[4,3- e]pyridin-5(4 H)-one is reported by condensation of aryl aldehydes, 4-hydroxy-6-methyl-2 H-pyran-2-one and 1-ethylpyrazol-5-amine in the presence of 10 mol% molecular I2 in ethanol under reflux conditions through a one-pot reaction. The present method offers several advantages such as use of a metal-free catalyst, being inexpensive, high yielding and environmental acceptability.

Transition metal-free decarboxylative alkylation reactions

This review summarizes recent advances in the transition metal-free decarboxylative alkylation of carboxylic acids and their derivatives.

Enantioselective annulation of enals with 2-naphthols by triazolium salts derived from l-phenylalanine

A series of chiral triazolium salts have been synthesized from methyl l-phenylalaninate hydrochloride. The NHCs derived from this class of novel triazolium salts were found to be highly efficient catalysts in the annulation reaction of enals and 2-naphthols. These reactions proceeded with high chemoselectivity and wide substrate scope affording enantioenriched β-arylsplitomicins in good yields with up to 96% ee.

Decarboxylative substitution of β-keto acids to benzylic alcohols catalyzed by molecular iodine

An efficient method for molecular iodine catalyzed decarboxylative substitution of β-keto acids with benzylic alcohols has been described.