Stereoselective Synthesis of 2-Carbamoyl-2-cyanocyclopropanecarboxylates by Tandem Oxidative Cyclization and Neighboring Group-Assisted Decarboxylation

Anion Cascade Reactions II: Synthesis of 3-Isoquinuclidone-Based Bridged Polycyclic Lactams

A facile and convenient anion cascade strategy was developed for the synthesis of bridged-ring amides in moderate to excellent yields in one step in the presence of tBuOK in EtOH under mild conditions, starting from various cheap and commercially available 2-cyanoacetamides and precisely designed straight-chain and annular 1,4-dienones. This simple protocol was generally applicable to a wide range of substrates with high chemical conversion and diastereoselectivity.

Synthesis of 3-Haloindoles via Cascade Oxidative Cyclization/Halogenation of 2-Alkenylanilines Mediated by PIDA and LiBr/KI

The treatment of 2-alkenylanilines with phenyliodine(III) diacetate (PIDA) and LiBr or KI in HFIP was found to afford the corresponding 3-haloindoles via cascade oxidative cyclization/halogenation encompassing oxidative C-N/C-X (X = Br, I) bond formations. A plausible mechanism involving the in situ formation of the reactive AcO-X (X = Br, I) from the reaction of PIDA and LiBr/KI was postulated.

Base-promoted highly efficient synthesis of nitrile-substituted cyclopropanes via Michael-initiated ring closure

A convenient and efficient annulation reaction has been developed for the general synthesis of dinitrile-substituted cyclopropanes in moderate to excellent yields. A variety of 2-arylacetonitriles and α-bromoennitriles were compatible under the standard conditions. The reaction was achieved through tandem Michael-type addition followed by intramolecular cyclization. The preliminary application of this method was confirmed by the synthesis of the 2,4-dioxo-3-azabicyclo[3.1.0]hexane scaffold.

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

Hypervalent iodine reagents have been developed as highly valuable reagents in synthetic organic chemistry during the past few decades. These reagents have been identified as key replacements of various toxic heavy metals in organic synthesis. Various synthetically and biologically important scaffolds have been developed using hypervalent iodine reagents either in stoichiometric or catalytic amounts. In addition, hypervalent iodine reagents have been employed for the synthesis of spirocyclic scaffolds via dearomatization processes. In this review, various approaches for the synthesis of spirocyclic scaffolds using hypervalent iodine reagents are covered including their stereoselective synthesis. Additionally, the applications of these reagents in natural product synthesis are also covered.

Organocatalysed Michael addition on arylmethylidenemalonates involving 4-(2-nitrophenyl)acetoacetate: diversity-oriented access to 8,9-dihydropyrido[1,2-a]indol-6(7H)-one and salicylate scaffolds

A diversity-oriented synthesis of 8,9-dihydropyrido[1,2-a]indol-6(7H)-one and salicylate scaffolds was achieved in high yields with excellent diastereoselectivities (≤96 : 4 dr) via an organocatalytic reaction of alkylidene malonates with 4-(2-nitrophenyl) acetoacetate.

Tandem halogenation/Michael-initiated ring-closing reaction of α,β-unsaturated nitriles and activated methylene compounds: one-pot diastereoselective synthesis of functionalized cyclopropanes

An efficient one-pot synthetic route to highly substituted cyclopropanes has been developed from readily available α,β-unsaturated nitriles and doubly activated methylene compounds under very mild conditions in a highly diastereoselective manner, which involves halogenation, Michael addition and intramolecular ring-closing reaction sequences.

Hypervalent iodine-catalyzed oxidative functionalizations including stereoselective reactions

Hypervalent iodine chemistry is now a well-established area of organic chemistry. Novel hypervalent iodine reagents have been introduced in many different transformations owing to their mild reaction conditions and environmentally friendly nature. Recently, these reagents have received particular attention because of their applications in catalysis. Numerous hypervalent iodine-catalyzed oxidative functionalizations such as oxidations of various alcohols and phenols, α-functionalizations of carbonyl compounds, cyclizations, and rearrangements have been developed successfully. In these catalytic reactions stoichiometric oxidants such as mCPBA or oxone play a crucial role to generate the iodine(III) or iodine(V) species in situ. In this Focus Review, recent developments of hypervalent iodine-catalyzed reactions are described including some asymmetric variants. Catalytic reactions using recyclable hypervalent iodine catalysts are also covered.