Boron Enabled Directed [2+2]‐ and Dearomative [4+2]‐Cycloadditions Initiated by Energy Transfer DOI Creative Commons

Souvik Adak,

Partha Sarathi Hazra,

Carter B. Fox

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 7, 2024

A strategy for the photosensitized [2+2]-cycloaddition between styrenyl dihaloboranes and unactivated allylamines to access cyclobutylboronates with control of stereochemistry regiochemistry is presented. The success reaction relies on temporary coordination in situ generated amines under mild conditions. In addition, cyclobutanes varying substitution patterns have been prepared using N-heterocycles as directing group. Manipulation C-B bond allows synthesis a diverse class from simple precursors. Moreover, these reactions lead complex heteroaromatic compounds, which significant utility medicinal chemistry. Finally, dearomative [4+2]-cycloaddition naphthalenes boron-enabled tethering has also uncovered synthesize 3-dimensional borylated building blocks.

Language: Английский

Synthesis of Borylated Carbocycles by [2 + 2]-Cycloadditions and Photo-Ene Reactions DOI
Jarett M. Posz,

Neetu Sharma,

Paige A. Royalty

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(14), P. 10142 - 10149

Published: March 27, 2024

Saturated bicyclic compounds make up a valuable class of building blocks in the development agrochemicals and pharmaceuticals. Here, we present synthesis borylated bicyclo[2.1.1]hexanes via crossed [2 + 2]-cycloaddition. Due to presence C–B bond, variety structures can be easily prepared that are not accessible by other methods. Moreover, rare photo-ene reaction is also disclosed, allowing for diastereoselective trisubstituted cyclopentanes.

Language: Английский

Citations

28
The Impact of Boron Hybridisation on Photocatalytic Processes DOI Creative Commons

Alessandro Marotta,

Callum E. Adams,

John J. Molloy

et al.

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(38)

Published: June 24, 2022

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

Language: Английский

Citations

56
Photosensitized [2+2]‐Cycloadditions of Alkenylboronates and Alkenes DOI
Yanyao Liu, Dongshun Ni,

Bernard G. Stevenson

et al.

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(25)

Published: April 21, 2022

A new strategy for the synthesis of highly versatile cyclobutylboronates via photosensitized [2+2]-cycloaddition alkenylboronates and alkenes is presented. The process mechanistically different from other processes in that energy transfer occurs with alkenylboronate as opposed to alkene. This allows an array diverse cyclobutylboronates. conversion these adducts compounds well their utility melicodenine C demonstrated.

Language: Английский

Citations

42
PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event DOI Creative Commons
Nicole Hanania, Nadim Eghbarieh, Ahmad Masarwa

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(25)

Published: April 11, 2024

Abstract While polyborylated alkenes are being recognized for their elevated status as highly valuable reagents in modern organic synthesis, allowing efficient access to a diverse array of transformations, including the formation C−C and C‐heteroatom bonds, potential energy‐transfer reactive groups has remained unexplored. Yet, this holds key generating elusive biradical species, which can be captured by olefins, thereby leading construction new highly‐borylated scaffolds. Herein, we report designed strategy photosensitized [2+2]‐cycloadditions poly‐borylated with various olefins enabling regioselective synthesis cyclobutane motifs, 1,1‐di‐, 1,1,2‐tri‐, 1,1,2,2‐tetra‐borylated cyclobutanes. In fact, these compounds belong family that presently lacks synthetic pathways. Interestingly, when α‐methylstyrene was used, reaction involves an interesting 1,5‐hydrogen atom transfer (HAT). Mechanistic deuterium‐labeling studies have provided insight into outcome process. addition, cyclobutanes then demonstrated useful selective oxidation processes resulting cyclobutanones γ‐lactones.

Language: Английский

Citations

11
Boronic Ester Enabled [2 + 2]-Cycloadditions by Temporary Coordination: Synthesis of Artochamin J and Piperarborenine B DOI
Yanyao Liu, Dongshun Ni, M. Kevin Brown

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(41), P. 18790 - 18796

Published: Oct. 6, 2022

A strategy for the photosensitized cycloaddition of alkenylboronates and allylic alcohols by a temporary coordination is presented. The process allows synthesis diverse range cyclobutylboronates. Key to development these reactions alcohol Bpin unit. This not only reaction proceed in an intramolecular manner but also high levels stereo regiocontrol. key aspect studies utility cycloadducts complex natural products artochamin J piperarborenine B.

Language: Английский

Citations

32
Hexafluoroisopropanol‐Promoted or Brønsted Acid‐Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides DOI

Ierasia Triandafillidi,

Nikolaos F. Nikitas,

Petros L. Gkizis

et al.

ChemSusChem, Journal Year: 2022, Volume and Issue: 15(4)

Published: Jan. 3, 2022

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

Language: Английский

Citations

27
Photochemical [2 + 2] Cycloaddition of Alkenes with Maleimides: Highlighting the Differences between N-Alkyl vs N-Aryl Maleimides DOI Creative Commons

Elpida Skolia,

Christoforos G. Kokotos

ACS Organic & Inorganic Au, Journal Year: 2022, Volume and Issue: 3(2), P. 96 - 103

Published: Dec. 8, 2022

Throughout the last 15 years, there has been increased research interest in use of light promoting organic transformations. [2 + 2] Cycloadditions are usually performed photochemically; however, literature precedent on reaction between olefins and maleimides is limited to a handful examples, focusing mainly N-aliphatic or using metal catalysts for visible-light driven reactions N-aromatic maleimides. Herein, we identify differences reactivity N-alkyl N-aryl For our optimized protocols, case maleimides, with alkenes proceeds under 370 nm irradiation absence an external photocatalyst, leading products high yields. In requires thioxanthone as photosensitizer 440 irradiation.

Language: Английский

Citations

23
Access to Complex Scaffolds Through [2 + 2] Cycloadditions of Strained Cyclic Allenes DOI
Matthew McVeigh, Jacob P. Sorrentino,

Allison T. Hands

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(22), P. 15420 - 15427

Published: May 20, 2024

We report the strain-induced [2 + 2] cycloadditions of cyclic allenes for assembly highly substituted cyclobutanes. By judicious choice trapping agent, complex scaffolds bearing heteroatoms, fused rings, contiguous stereocenters, spirocycles, and quaternary centers are ultimately accessible. Moreover, we show that resulting cycloadducts can undergo thermal isomerization. This study provides an alternative strategy to photochemical accessing functionalized cyclobutanes, while validating use underexplored strained intermediates architectures.

Language: Английский

Citations

6
The current utility and future potential of multiborylated alkanes DOI

Kane A. C. Bastick,

Dean D Roberts,

Allan J. B. Watson

et al.

Nature Reviews Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 26, 2024

Language: Английский

Citations

5
A Modular Access to 1,2‐ and 1,3‐Disubstituted Cyclobutylboronic Esters by Consecutive Radical Additions DOI

Jean Michalland,

Nicolas Casaretto, Samir Z. Zard

et al.

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(3)

Published: Oct. 30, 2021

A modular approach to substituted cyclobutylboronic esters is described. It proceeds by successive intermolecular radical additions of xanthates pinacolato 1-cyclobutenylboronate and bicyclo[1.1.0]but-1-ylboronate. Success hinges on tuning the stability α-boryl exploiting stabilizing influence trivalent boronic ester slightly destabilizing cyclobutane, which increases σ-character radical. Reductive removal xanthate group finally provides a range 1,2- 1,3-disubstituted esters. The contrast with cyclopropylboronic striking, since strong destabilization highly strained cyclopropane ring allows first addition take place but not second. Furthermore, adducts are geminal xanthyl that can be converted into cyclobutanones. This chemistry furnishes would quite difficult obtain otherwise thus complements existing methods.

Language: Английский

Citations

30