Construction of Complex Cyclobutane Building Blocks by Photosensitized [2 + 2] Cycloaddition of Vinyl Boronate Esters

Scholz, Spencer O.; Kidd, Jesse B.; Capaldo, Luca; Flikweert, Niecia E.; Littlefield, Rowan M.; Yoon, Tehshik P.

doi:10.1021/acs.orglett.1c00938

Cited by 38 publications

(40 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to improve the reaction yield, two different approaches were then envisaged. In the first approach, we were inspired by the pioneering studies of Lewis on Lewis‐acid complexes in photochemical reactions, [15] as well as similar studies by Yoon and co‐workers, Bach and co‐workers, and many others [7j,16] . We questioned whether a similar phenomenon can be employed utilizing a Brønsted acid (protonation).…”

Section: Resultsmentioning

confidence: 99%

Hexafluoroisopropanol‐Promoted or Brønsted Acid‐Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides

et al. 2022

View full text Add to dashboard Cite

Although the use of light stimulating organic transformations has been known for more than a century, there is an increasing research interest on expanding the established knowledge. While [2 + 2] cycloadditions are promoted photochemically, literature precedent on the reaction between alkynes and maleimides is limited and only a handful of examples exist, focusing mainly on N-aliphatic maleimides. Herein, the differences in reactivity between N-alkyl and N-aryl maleimides were identified, and the use of hexafluoroisopropanol (HFIP) or trifluoroacetic acid (TFA) as viable solutions was proposed in order to achieve high yields. In the case of N-alkyl maleimides, both HFIP-mediated or TFA-promoted reactions were established using LED 370 nm irradiation, without the use of an external photocatalyst. In the case of N-aryl maleimides, thioxanthone (THX) was employed as the energy transfer photocatalyst along with LED 427 nm irradiation and HFIP. Mechanistic studies were performed, supporting the pivotal role of HFIP or TFA, in acquiring good to high yields in both classes of maleimides.

show abstract

Section: Resultsmentioning

confidence: 99%

Hexafluoroisopropanol‐Promoted or Brønsted Acid‐Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The resulting crude was purified by chromatography on silica gel ( n -hexanes/EtOAc, under gradient) affording product 1u as a yellow oil (532 mg, 53%). The spectral data for this compound correspond to the literature …”

Section: Methodsmentioning

confidence: 99%

Inter/Intramolecular Cascade of 1,6-Enynes Catalyzed by All-Metal Aromatic Tripalladium Complexes and Carboxylic Acids

et al. 2021

View full text Add to dashboard Cite

Trinuclear all-metal aromatic clusters are an original class of molecules with a cyclic and planar metal core. Characterized by peculiar metal–metal delocalized bonds, they represent a new frontier in transition-metal catalysis. We report a study on C–C-forming reactions of polyunsaturated substrates catalyzed by trinuclear all-metal aromatic palladium clusters. The synthesis of two new families of tricyclic compounds was obtained with a broad functional group tolerance under mild reaction conditions. A peculiar regio- and diastereoselectivity characterized the method, demonstrating that trinuclear palladium complexes are complementary to their popular mononuclear peers. Furthermore, preliminary studies on the mechanism of these polycyclization reactions revealed unique features of the homogeneous catalytic system.

show abstract

“…It is pertinent to note this allowed a series of boron functionalities of different hybridisation states to be compatible with model reaction conditions. Recently Brown and co‐workers provided a striking example demonstrating EnT‐catalysed intermolecular [2+2] cycloaddition of alkenyl boronic esters (Scheme 18, bottom) [103] . Mechanistic studies identified a triplet energy transfer mechanism highlighting that energy is transferred to the alkenyl (styrene or diene) organoboron species.…”

Section: Photochemical Strategies Retaining the C−b Bondmentioning

confidence: 99%

The Impact of Boron Hybridisation on Photocatalytic Processes

2022

View full text Add to dashboard Cite

Recently the fruitful merger of organoboron chemistry and photocatalysis has come to the forefront of organic synthesis, resulting in the development of new technologies to access complex (non)borylated frameworks. Central to the success of this combination is control of boron hybridisation. Contingent on the photoactivation mode, boron as its neutral planar form or tetrahedral boronate can be used to regulate reactivity. This Minireview highlights the current state of the art in photocatalytic processes utilising organoboron compounds, paying particular attention to the role of boron hybridisation for the target transformation.

show abstract

Construction of Complex Cyclobutane Building Blocks by Photosensitized [2 + 2] Cycloaddition of Vinyl Boronate Esters

Cited by 38 publications

References 62 publications

Hexafluoroisopropanol‐Promoted or Brønsted Acid‐Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides

Hexafluoroisopropanol‐Promoted or Brønsted Acid‐Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides

Inter/Intramolecular Cascade of 1,6-Enynes Catalyzed by All-Metal Aromatic Tripalladium Complexes and Carboxylic Acids

The Impact of Boron Hybridisation on Photocatalytic Processes

Contact Info

Product

Resources

About