Directing the Stereoselectivity of the Claisen Rearrangement to Form Cyclic Ketones with Full Substitution at the α-Positions.

We report an enantioselective synthesis of cyclic ketones with full substitutions at the α-positions in a highly diastereoselective manner. Our method is achieved by subjecting substrate motifs in 2-allyloxyenones to chiral organomagnesium reagents, which trigger the Claisen rearrangement upon direct 1,2-carbonyl addition. The observed diastereoselectivity of the allyl migration is proposed to originate from the intramolecular chelation of the magnesium alkoxide to the allyloxy moiety.

Transition metal-catalyzed regioselective functionalization of carbazoles and indolines with maleimides.

The directing group-assisted regioselective C-H activation of carbazoles and indolines is achieved transition metal-catalyzed reactions. This C-H functionalization protocol provides a rapid approach to install diversely functionalized succinimide groups at the C-1 position of the carbazole moiety. In addition, this protocol demonstrates the intrinsic reactivity of indolines in providing C-2 succinimide-substituted indoles cascade direct oxidation and C-H functionalization.

Palladium-catalyzed synthesis of β-hydroxy compounds a strained 6,4-palladacycle from directed C-H activation of anilines and C-O insertion of epoxides.

A palladium-catalyzed C-H activation of acetylated anilines (acetanilides, 1,1-dimethyl-3-phenylurea, 1-phenylpyrrolidin-2-one, and 1-(indolin-1-yl)ethan-1-one) with epoxides using -coordinating directing groups was accomplished. This C-H alkylation reaction proceeds formation of a previously unknown 6,4-palladacycle intermediate and provides rapid access to regioselectively functionalized β-hydroxy products. Notably, this catalytic system is applicable for the gram scale mono-functionalization of acetanilide in good yields.

Palladium-Catalyzed Direct Oxidative C-H Activation/Annulation for Regioselective Construction of -Acylindoles.

A Pd(II)-catalyzed C(sp)-H/C(sp)-H coupling/annulation of anilides and α-dicarbonyl compounds for the synthesis of diverse -acyl indoles is described. The reaction is achieved by cascade C-H activation, coupling, and intramolecular cyclization. This protocol provides a variety of indoles with high functional group tolerance and excellent regioselectivity.

Chitosan-derived N-doped carbon catalysts with a metallic core for the oxidative dehydrogenation of NH-NH bonds.

Sustainable metal-encased (Ni-Co/Fe/Cu)@N-doped-C catalysts were prepared from bio-waste and used for the oxidative dehydrogenation reaction. A unique combination of bimetals, N doping, and porous carbon surfaces resulted in the formation of the effective "three-in-one" catalysts. These N-doped graphene-like carbon shells with bimetals were synthesized the complexation of metal salts with chitosan and the subsequent pyrolysis at 700 °C.

Rhodium(iii)-catalyzed regioselective distal ortho C-H alkenylation of N-benzyl/furanylmethylpyrazoles directed by N-coordinating heterocycles.

C-H activation of challenging N-benzylpyrazoles was accomplished by employing rhodium(iii) catalysis. This C-H activation reaction proceeds via a six-membered rhodacycle intermediate and enables distal regioselective alkenyl-functionalization on the aromatic ring of N-benzylpyrazoles without the formation of bis-adducts. High functional group tolerance, low catalyst loading, and superior reactivity of olefin moieties towards N-benzylpyrazoles are some of the attractive features of this protocol.

Ruthenium catalyzes the synthesis of γ-butenolides fused with cyclohexanones.

Ruthenium(II)-catalyzed reactions of cyclic diazodicarbonyl compounds with β-ketoamides for chemo- and stereoselective construction of cyclohexanone-fused γ-butenolides are described. This study represents the first example of the addition of an enol substrate which is formed by the tautomerization of the β-ketoamides to the electrophilic carbene center for unusual cyclization through amide cleavage. The combined experimental and computational studies shed light on the mechanistic pathway favouring the unusual ring formation reaction instead of the involvement of the general carbonyl ylide intermediates for the product generation.

Synergistic Indium and Silver Dual Catalysis: A Regioselective [2 + 2 + 1]-Oxidative N-Annulation Approach for the Diverse and Polyfunctionalized N-Arylpyrazoles.

Indium(III)/silver(I)-catalyzed [2 + 2 + 1] annulation of arylhydrazine hydrochlorides with β-enamino esters via multicomponent reactions for the construction of diverse and multisubstituted N-arylpyrazoles has been demonstrated. The oxidative cycloaddition proceeds via a cascade triple Michael addition/elimination/air oxidation. This novel protocol provides a rapid and efficient synthetic route to various 3,4-diester-substituted N-arylpyrazoles.

Total synthesis of the natural product EBC-329.

The first total synthesis of an anti-leukemic diterpene natural product EBC-329 (1) has been accomplished starting from readily available 6,6-dimethyl-3-oxabicyclo[3.1.0]hexane-2,4-dione (7).