Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 8 de 8
Filter
Add more filters










Database
Language
Publication year range
1.
Org Lett ; 24(46): 8559-8563, 2022 Nov 25.
Article in English | MEDLINE | ID: mdl-36351082

ABSTRACT

The removal of the tetrafluoropyridinyl group tethered to a sulfur atom using a complex of N-heterocyclic carbene (NHC) with borane is described. The reaction is performed under blue light irradiation with a disulfide as radical initiator. The selective cleavage of S-Ar in preference to the weaker S-Alk bond is achieved as a result of aromatic radical substitution of the thiyl group by a NHC-stabilized boron-centered radical. Alkyl thiols, which are the primary products of the dearylation, are in situ oxidized or alkylated, affording disulfides or sulfides, respectively.

2.
Org Lett ; 23(10): 3919-3922, 2021 May 21.
Article in English | MEDLINE | ID: mdl-33929210

ABSTRACT

Interaction of sulfides bearing a tetrafluoropyridinyl group with bis(catecholato)diboron followed by treatment with pinacol and triethylamine affording pinacol boronic esters is described. The reaction is promoted by an organic photocatalyst (3DPA2FBN) under irradiation with 400 nm light, and works with primary, secondary, and tertiary sulfides. The electron depleting character of the fluorinated pyridine fragment plays an important role in generating alkyl radicals.

3.
Angew Chem Int Ed Engl ; 60(6): 2849-2854, 2021 02 08.
Article in English | MEDLINE | ID: mdl-33146419

ABSTRACT

A metal- and catalyst-free thiyl-radical-mediated activation of alkanes is described. Tetrafluoropyridinyl disulfide is used to perform thiolation of the C-H bonds under irradiation with 400 nm light-emitting diodes. The key C-H activation step is believed to proceed via hydrogen-atom abstraction effected by the fluorinated thiyl radical. Secondary, tertiary, and heteroatom-substituted C-H bonds can be involved in the thiolation reaction. The resulting sulfides have wide potential as photoredox-active radical precursors in reactions with alkenes and heteroarenes.

4.
Org Lett ; 22(6): 2409-2413, 2020 Mar 20.
Article in English | MEDLINE | ID: mdl-32118450

ABSTRACT

A reaction of an iododifluoromethylphosphonium salt with unactivated alkenes mediated by peri-xanthenoxanthene under blue-light irradiation is described. The reaction proceeds via activation of the carbon-iodine bond to generate (phosphonio)difluoromethyl radical cation, which attacks the double bond with subsequent quenching by the iodine. The intermediate phosphonium salts are easily hydrolyzed, furnishing products of iododifluoromethylation of alkenes.

5.
Chem Commun (Camb) ; 55(9): 1314-1317, 2019 Jan 24.
Article in English | MEDLINE | ID: mdl-30633258

ABSTRACT

A method for the assembly of the halodifluoromethyl group (CF2X, X = Cl, Br, I) is described. The reaction involves the light-mediated substitution of the triphenylphosphine by halide anions in readily accessible gem-difluorinated phosphonium salts.

6.
J Org Chem ; 82(1): 745-753, 2017 01 06.
Article in English | MEDLINE | ID: mdl-27943669

ABSTRACT

A method for the synthesis of 3-fluoroindoles from N-arylamines substituted with the CF2I group is described. The reaction is mediated by a ruthenium photocatalyst in the presence of a substoichiometric amount of triphenylphosphine upon irradiation with blue light. The starting N-arylamines are readily obtained by nucleophilic iododifluoromethylation of iminium ions.

7.
Org Lett ; 18(5): 996-9, 2016 Mar 04.
Article in English | MEDLINE | ID: mdl-26862998

ABSTRACT

gem-Difluorinated phosphonium salts, which are readily obtained from aldehydes and difluoromethylene phosphobetaine, can serve as a source of radicals under reductive conditions. An iridium complex or Hantzsch ester was used as a one-electron reducing agent when irradiated with visible light. The fluorinated radicals were trapped with various alkenes, leading to products either via a photoredox cycle (for the iridium catalyst) or via a hydrogen atom transfer (for the Hantzsch ester).

8.
Angew Chem Int Ed Engl ; 54(17): 5218-22, 2015 Apr 20.
Article in English | MEDLINE | ID: mdl-25726937

ABSTRACT

Four new well-defined Cu(I) complexes bearing a C2 F5 ligand have been prepared and fully characterized: [(Ph3 P)2 CuC2 F5 ] (2), [(bpy)CuC2 F5 ] (3), [(Ph3 P)Cu(phen)C2 F5 ] (4), and [(IPr*)CuC2 F5 ] (5). X-ray structures of all four have been determined, showing that the C2 F5 -ligated Cu atom can be di- (5), tri- (2 and 3), and tetracoordinate (4). The mixed phen-PPh3 complex 4 is a highly efficient fluoroalkylating agent for a broad variety of acid chlorides. This high-yielding transformation represents the first general method for the synthesis of RCOC2 F5 from the corresponding RCOCl.


Subject(s)
Chlorides/chemistry , Coordination Complexes/chemistry , Copper/chemistry , Fluorine/chemistry , Crystallography, X-Ray , Ketones/chemical synthesis , Ketones/chemistry , Molecular Conformation , Phenanthrolines/chemistry
SELECTION OF CITATIONS
SEARCH DETAIL
...