Synthesis of Ferrocene 1,3-Derivatives by Distal C-H Activation.

The third position of cyclopentadienyl ring of a monosubstituted ferrocene has remained as an inaccessible chemical space for direct functionalization. Until recently, functionalizing the C(3)-position while bypassing the predominantly active C(2)-position is the most challenging task. Herein, we report a distal C-H functionalization of monosubstituted ferrocenes using an easily removable directing group with precise site-selectivity, under a PdII / mono-N-protected amino-acid ligand catalytic system. The robust synthetic protocol leads to the synthesis of ferrocene 1,3-derivatives with broad scope in olefins while functionalizing ferrocenyl methylamine in moderate to good yields via a highly strained ferrocene appended 12-membered palladacycle intermediate.

Catalyst-Controlled Chemodivergent Reactivity of Vinyl Cyclopropanes: A Selective Approach toward Indoles and Aniline Derivatives.

Herein, we disclose a catalyst-controlled chemodivergent approach to access C2-substituted indoles and diverse aniline derivatives with good chemo- and stereoselectivity by employing vinylcyclopropanes (VCPs) as coupling partners via a tandem C-H/C-C activation/annulation strategy. The key feature of this work is the divergent reactivity profile showcased by VCPs, going beyond allylation under a high-valent Rh-/MPAA catalyst system.

Activated alkene dependent one-pot, three-component aza-Morita-Baylis-Hillman reaction of ferrocenealdehyde: synthesis of highly functionalized diverse ferrocene derivatives.

Activated alkene dependent one-pot, three-component aza-Morita-Baylis-Hillman (aza-MBH) reaction of ferrocenealdehyde afforded simple aza-MBH adduct of ferrocenealdehyde, unusual piperidine, ß-amino acid residue, and γ-ketoester derivatives of ferrocene in good yield. The synthetic protocol with MVK has led to an unexpected ferrocenyl piperidine derivative in an excellent yield via diastereoselective domino aza-Michael/double Aldol pathway. Plausible mechanisms for the formation of unusual products and diastereoselectivity have also been described. The products can be used for the concise synthesis of ferrocenyl nitrogen heterocycles and bioconjugates.

Pyridine core activation via 1,5-electrocyclization of vinyl pyridinium ylides generated from bromo isomerized Morita-Baylis-Hillman adduct of isatin and pyridine: synthesis of 3-spirodihydroindolizine oxindoles.

An activation of the pyridine nucleus has been achieved via 1,5-electrocyclization of vinyl pyridinium ylides generated from bromo isomerized Morita-Baylis-Hillman adducts of isatin and pyridine under basic conditions. The method has been successfully applied for an efficient synthesis of a number of 3-spirodihydroindolizine-2-oxindoles, which have been found as core structure of secoyohimbane and heteroyohimbane alkaloid natural products.

Synthesis of novel functionalized 3-spiropyrrolizidine and 3-spiropyrrolidine oxindoles from Baylis-Hillman adducts of isatin and heteroaldehydes with azomethine ylides via [3+2]-cycloaddition.

A novel regioselective synthesis of a number of functionalized 3-spiropyrrolizidine and 3-spiropyrrolidine oxindoles from Baylis-Hillman adducts of isatin and heteroaldehydes via [3+2] cycloaddition of azomethine ylides in excellent yields has been reported.