Nucleophilic Ring Opening of Donor-Acceptor Cyclopropanes through Umpolung Reactivity of Organochlorophosphines: Phosphine Oxide-Functionalized Boron-Pendanted Compounds.

We present a novel set of frustrated Lewis pair (FLP) systems that exhibit a remarkable ability to promote the ring opening of donor-acceptor cyclopropanes (DACs). This FLP-promoted protocol offers umpolung reactivity of RRPCl/CN (R, R = aryl, alkyl) toward DACs via nucleophilic ring-opening reactions to provide phosphinated boron-pendanted diester compounds. This novel approach exhibits the dual role of BF·OEt as an activator and a reactant.

Metal-Free Switchable Chemo- and Regioselective Alkylation of Oxindoles Using Secondary Alcohols.

In this study, we have disclosed N-alkylation and C-alkylation reactions of 2-oxindoles with secondary alcohols. Interestingly, these chemoselective reactions are tunable by changing the reaction conditions. Utilization of protic solvent and Brønsted acid catalyst afforded C-alkylation, whereas, aprotic solvent and Lewis acid catalyst afforded N-alkylation of 2-oxindoles in good to excellent yields.

Synthetic F labeled biomolecules that are selective and promising for PET imaging: major advances and applications.

The concept of positron emission tomography (PET) based imaging was developed more than 40 years ago. It has been a widely adopted technique for detecting and staging numerous diseases in clinical settings, particularly cancer, neuro- and cardio-diseases. Here, we reviewed the evolution of PET and its advantages over other imaging modalities in clinical settings.

Copper-Catalyzed Chemoselective O-Arylation of Oxindoles: Access to Cyclic Aryl Carboxyimidates.

We have developed a highly efficient base- and additive-free chemoselective CuO-catalyzed strategy for the O-arylation of 2-oxindoles to synthesize 2-phenoxy-3-indole and 2-phenoxy-1-indole derivatives in the presence of diaryl iodonium salts. This method offers a variety of O-arylated oxindoles in good to excellent yields under relatively milder reaction conditions. Furthermore, this methodology was extended for the O-arylation of 2-pyridinone and isoindoline-1-one derivatives as well.

Synthesis of Indole-Fused Dihydrothiopyrano Scaffolds (3 + 3)-Annulations of Donor-Acceptor Cyclopropanes with Indoline-2-Thiones.

A new methodology for the synthesis of -haloindole-fused dihydrothiopyrano derivatives (3 + 3)-annulation of donor-acceptor cyclopropanes (DACs) with indoline-2-thiones in the presence of Sc(OTf) as a Lewis acid catalyst has been developed. This protocol provides a variety of indole-fused dihydrothiopyrano molecules in good to excellent yields, which architecturally resemble other indole-fused tricyclic molecules having potential medicinal value. In addition, we have described a detailed reaction mechanism and transformation of the furnished product into -fused thiazino indole molecule.

A metal-free BF·OEt mediated chemoselective protocol for the synthesis of propargylic cyclic imines.

A chemoselective and metal/additive-free protocol for the synthesis of propargylic cyclic imine derivatives (3 + 2)-cycloaddition of donor-acceptor cyclopropanes and alkynylnitriles in the presence of BF·OEt has been established. The newly developed methodology provided access to a variety of propargylic cyclic imines in good to excellent yields. In addition, the synthesis of propargylic amines and the corresponding very stable enol derivatives from the title compound is also explored.