Regioselective ortho halogenation of N-aryl amides and ureas via oxidative halodeboronation: harnessing boron reactivity for efficient C-halogen bond installation.

The installation of the C-halogen bond at the ortho position of N-aryl amides and ureas represents a tool to prepare motifs that are ubiquitous in biologically active compounds. To construct such prevalent bonds, most methods require the use of precious metals and a multistep process. Here we report a novel protocol for the long-standing challenge of regioselective ortho halogenation of N-aryl amides and ureas using an oxidative halodeboronation. By harnessing the reactivity of boron over nitrogen, we merge carbonyl-directed borylation with consecutive halodeboronation, enabling the precise introduction of the C-X bond at the desired ortho position of N-aryl amides and ureas. This method offers an efficient, practical, and scalable solution for synthesizing halogenated N-heteroarenes under mild conditions, highlighting the superiority of boron reactivity in directing the regioselectivity of the reaction.

BF3 ⋠Et2 O-Catalyzed Selective C-4 Alkylation of Isoquinolin-1(2H)-ones Employing p-Quinone Methides.

The direct C-4 alkylation of isoquinolin-1(2H)-one moiety is a challenging transformation in organic synthesis. Here we present a practical and efficient synthesis of C-4 alkylated isoquinolin-1(2H)-ones through conjugate addition of isoquinolin-1(2H)-ones to p-quinone methides for the first time. The process is facilitated by Lewis acid catalysis and this operationally straightforward, mild, metal-free and one-pot transformation provides a wide range of C-4 alkylated isoquinolin-1(2H)-ones at ambient temperature in good to excellent yields.

Palladium-Catalyzed Oxidative Cyclization of α-Allenols in the Presence of TBN: Access to 3(2H)-Furanones.

A new palladium-catalyzed oxidative cyclization of α-allenols is described. The readily accessible α-allenols participate in intra-molecular oxidative cyclization in the presence of TBN to grant access to multisubstituted 3(2H)-furanones, which are common motifs in several biologically important natural products and pharmaceuticals.

Silver-Catalyzed Cascade Cyclization/1,6-Conjugate Addition of Homopropargyl Sulfonamides to p-Quinone Methides: An Approach to Diverse 3-Diarylmethine Substituted Dihydropyrroles.

A silver-catalyzed cycloisomerization/1,6-conjugate addition of homopropargyl sulfonamides to p-quinone methides to access diverse diarylmethine substituted dihydropyrroles has been disclosed. The reaction pathway involves an intramolecular cascade cyclization of homopropargyl sulfonamides to generate a highly reactive dihydropyrrole intermediate in situ followed by conjugate addition with p-quinone methides. This method provides an efficient and scalable route for the synthesis of 3-diarylmethine substituted dihydropyrroles, in one pot.

1,6-Conjugate addition initiated formal [4+2] annulation of p-quinone methides with sulfonyl allenols: a unique access to spiro[5.5]undeca-1,4-dien-3-one scaffolds.

An expedient one-pot synthesis of carbocyclic spiro[5.5]undeca-1,4-dien-3-ones via 1,6-conjugate addition initiated formal [4+2] annulation sequences by employing p-quinone methides and sulfonyl allenols is presented. Furthermore, this synthetic protocol tolerates a wide variety of p-quinone methides and sulfonyl allenols and affords the corresponding structurally unique spiro[5.5]undeca-1,4-dien-3-ones in good yield under mild reaction conditions.

Total Synthesis of Marine Natural Products Serinolamide A and Columbamide D.

In this report, an expeditious synthesis of two new biologically active marine natural products serinolamide A and columbamide D is documented. This convergent approach involves the key steps such as hydrolytic kinetic resolution, cross metathesis, Grignard reaction, Johnson-Claisen rearrangement, Mitsunobu, and so forth. Both of the target molecules were obtained from a common precursor (R)-7 with high enantioselectivity, less synthetic steps, and in good overall yields (serinolamide A 66% and columbamide D 62%).

Transition-Metal-Free Benzannulation of Tricarbonyl Derivatives with Arynes: Access to 1,3-Dinaphthol Precursors for the Synthesis of Rhodamine Dye Analogues.

Herein, we report a transition-metal-free annulation reaction of benzynes and 1,3-oxopentanedioate for the synthesis of highly functionalized naphthalene derivatives for the first time. Additionally, the representative naphthalene derivatives have been successfully transformed into the new series of rhodamine dye analogues.

Transition metal free regio-selective C-H hydroxylation of chromanones towards the synthesis of hydroxyl-chromanones using PhI(OAc)2 as the oxidant.

The chromanone scaffold is considered as a privileged structure in drug discovery. Herein, we report a highly efficient PhI(OAc)2 mediated regioselective, direct C-H hydroxylation of chromanones. This method offers easy access to substituted 6-hydroxy chromanones in moderate to good isolated yields, thus paving the way for their pharmaceutical studies.