Wittig olefination “baking powder”: a hexameric halogen-bonded phosphonium salt cage for encapsulation and mechanochemical transformation of small-molecule carbonyl compounds

We report a hexameric supramolecular cage assembled from the components of a Wittig-type phosphonium salt, held together by charge-assisted R-Br· · ·Br-· · ·Br-R halogen bonds. The cage reliably encapsulates small polar molecules, including aldehydes and ketones, to provide host-guest systems in which components are pre-formulated in a near-ideal stoichiometry for a base-activated Wittig olefination in the solid-state. These pre-formulated solids enable a molecular-level “baking powder” approach for solvent-free Wittig reactions, based on a design of solid-state reactivity in which the host for molecular inclusion also acts as a complementary reagent for the chemical transformation of an array of guests. These host-guest solid-state complexes can also act as supramolecular surrogates to their Wittig olefination vinylbromide products, in a Sonogashira-type coupling that enables one-pot mechanochemical conversion of an aldehyde to an enediyne.

Photocatalytic Cycloaddition Reaction of Triarylphosphines with Alkynes Forming Cyclic Phosphonium Salts

Herein reported is a photocatalytic cycloaddition reaction of triarylphosphines with alkynes. Phosphonium salts of unique bicyclic structures are synthesized through a radical pathway under mild reaction conditions. The phosphonium salts are subjected to the Wittig olefination reaction to afford structurally interesting phosphine oxides.

Photocatalytic Cycloaddition Reaction of Triarylphosphines with Alkynes Forming Cyclic Phosphonium Salts

Herein reported is a photocatalytic cycloaddition reaction of triarylphosphines with alkynes. Phosphonium salts of unique bicyclic structures are synthesized through a radical pathway under mild reaction conditions. The phosphonium salts are subjected to the Wittig olefination reaction to afford structurally interesting phosphine oxides.

Xylochemical Synthesis and Biological Evaluation of Shancigusin C and Bletistrin G

The biological activities of shancigusin C (1) and bletistrin G (2), natural products isolated from orchids, are reported along with their first total syntheses. The total synthesis of shancigusin C (1) was conducted by employing the Perkin reaction to forge the central stilbene core, whereas the synthesis of bletistrin G (2) was achieved by the Wittig olefination followed by several regioselective aromatic substitution reactions. Both syntheses were completed by applying only renewable starting materials according to the principles of xylochemistry. The cytotoxic properties of shancigusin C (1) and bletistrin G (2) against tumor cells suggest suitability as a starting point for further structural variation.

Wittig Reactions of Maleimide Derived Stabilized Ylides with Alkyl Pyruvates: Concise Approach to Methyl Ester of (±)-Chaetogline A

A facile synthesis of methyl ester of chaetogline A is reported starting from the corresponding methyl 1-methyltryptophanate derived maleimide. A stereoselective Wittig olefination with a carbonyl function in methyl pyruvate followed by phosphorous pentoxide induced regioselective dehydrative cyclization are the essential reactions. An acid induced thermodynamically driven stereoselective β- to α-position migration of the exocyclic carbon−carbon double unit in ethyl tetrahydroindolizinoindolylidenepropanoate is described.

Boron-Wittig olefination with gem-bis(boryl)alkanes

Boron-Wittig reaction as the condensation of lithium α-bis(boryl)carbanions with carbonyl derivatives on route to substituted borylalkenes.

Synthesis and Molecular Properties of Partially Fluorinated DNTTs

1,2,3,4-Tetrafluoro-dinaphthothienothiophene (F4DNTT) and 1,2,3,4,8,9,10,11-octafluoro-dinaphthothienothiophene (F8DNTT) were synthesized via bisthiomethyl alkene intermediates which were accessible by McMurry coupling or Wittig olefination of partially fluorinated naphthalene precursors. DFT-based electronic structure calculations, X-ray absorption spectroscopy (NEXAFS) and UV/Vis measurements were used for HOMO/LUMO gap determination and to analyse the electronic structures of the partially fluorinated DNTTs. Reduced exciton binding was observed in thin films