Modular synthesis of unsymmetrical indolyl diketones from ynediones sequential aza-Michael addition/C-H functionalization.

Herein, we disclose an efficient approach for the synthesis of unsymmetrical indolyl diketones from easily accessible 1,2-alkynediones involving a sequential aza-Michael addition/C-H Functionalization process. The two-step, one-pot strategy involves the aza-Michael addition of an aniline generating the -aryl enaminones followed by iodine-mediated C-H functionalization.

Divergent Synthesis of Unsymmetrical Bis-heteroaryl Ketones via Base-Promoted Cascade Reactions of 1,2-Alkynedione-Derived -Propargylic β-Enaminones.

Herein we disclose a transition-metal-free, one-pot two-step strategy for the synthesis of unsymmetrical bis-heteroaryl ketones. -propargylic β-enaminones generated by the Michael addition of propargylamines onto heteroaryl 1,2-alkynediones have been utilized as synthetic equivalents of pyridine or pyrrole scaffolds. The use of alcohol as a solvent resulted in the formation of 2-alkoxylated pyridine scaffold, whereas the use of DMSO promoted the formation of a pyrrole motif.

Diastereoselective synthesis of functionalized spiroindolines intramolecular -iodocyclization/nucleophile addition cascade reactions of indole-tethered ynones.

Herein, we describe a highly diastereoselective approach for synthesizing polyfunctionalized spiroindolines from indolyl-ynones involving an -iodocyclization/nucleophile addition cascade. The developed strategy allows the formation of a spirocyclic core and the installation of two functional groups in a single operation. Also this strategy is accompanied by the generation of two C-C and one C-I bonds and two contiguous stereocenters.

Ag(I)-catalyzed dearomatizing spirocyclization/nucleophile addition cascade reactions of indole-tethered ynones.

Ag(I)-catalyzed highly diastereoselective construction of divergent spiroindolines is disclosed herein. The approach proceeds dearomatizing spirocyclization of indole-tethered ynones followed by C-nucleophile or hydride trapping. The established strategy is accompanied by the generation of two new C-C bonds and two contiguous stereocenters.

Iodocycloisomerization/Nucleophile Addition Cascade Transformations of 1,2-Alkynediones.

A general electrophilic iodocyclization/nucleophile addition cascade transformation for 1,2-alkynediones for the synthesis of various oxygen heterocycles and access to regioselective alkyne hydroxylation is reported. Furan-tethered ynediones resulted in the construction of -enol ethers via carbonyl-alkyne cyclization-initiated heteroarene dearomatization, whereas other (hetero)arene-, alkenyl-, and alkyl-tethered ynediones resulted in the formation of highly functionalized 3(2)-furanones. Importantly, the developed domino protocols involve the construction of important heterocyclic scaffolds and installation of two functional groups in a single operation.

Gold(I)-Catalyzed Cycloisomerization-Indole Addition Cascade: Synthesis of 3(2)-Furanone-Incorporated Unsymmetrical 3,3'- Bis(indolyl)methanes.

An unprecedented Au(I)-catalyzed domino intramolecular carbonyl-alkyne cyclization/indole addition strategy has been disclosed here. This generalized strategy enables the synthesis of 3(2)-furanone-incorporated unsymmetrical bis(indolyl)methanes with generation of a stereocenter at the furanone junction from easily accessible indole-tethered ynediones. In addition, this present protocol could also be extended for the synthesis of a number of indolyl-(hetero)arylmethanes by employing a variety of (hetero)arenes as a nucleophile coupling partner.

Photo-induced 1,2-carbohalofunctionalization of C-C multiple bonds via ATRA pathway.

Radical vicinal carbohalofunctionalization of C-C multiple bonds via atom transfer processes constitutes an efficient method for the construction of halogenated building blocks with complete atom economy via radical cleavage of a pre-existing carbon-halogen σ-bond of an atom transfer reagent and their transposition over the π-bond of alkenes and alkynes. This review summarizes the recent advances in the photo-induced version of this class of transformations. A variety of transition-metal complexes, organic dyes, phosphines, amines, phenols and aldehydes were utilized as catalysts for the cleavage of the existing carbon-halogen bond of the corresponding atom transfer reagent in the presence of a light source.

Chiral Transient Directing Group Strategies in Asymmetric Synthesis.

The development of novel methodologies for catalytic enantioselective functionalization reactions enabled by chiral transient directing groups is accompanying in a paradigm shift in the field of asymmetric synthesis. In particular, these highly atom- and step-economic enantioinduction processes commonly proceed either via enantioselective C-H functionalization, or via enantioselective hydroarylation of the pro-chiral substrates generating point, axial or planar chirality. The use of the transient directing group strategy in C-H functionalizations precludes the stoichiometric installations and removal of directing groups and enables efficient, more compatible and economical chemical routes.

Heteroarene-tethered Functionalized Alkyne Metamorphosis.

Heteroarene-tethered functionalized alkynes are multipotent synthons in organic chemistry. This detailed Review described herein offers a thorough discussion of the metamorphosis of heteroarene-tethered functionalized alkynes, an area which has earned much attention over the past decade in the straightforward synthesis of architecturally complex heterocyclic scaffolds in atom and step economic manner. Depending upon the variety of functionalized alkynes, this Review is divided into multiple sections.