3 research outputs found
Primary Amines as Directing Groups in the Ru-Catalyzed Synthesis of Isoquinolines, Benzoisoquinolines, and Thienopyridines
Isoquinolines, benzoisoquinolines,
thienoÂ[3,2-<i>c</i>]Âpyridines and fused heteroarylÂ[2,3-<i>c</i>] pyridines,
with a wide variety of substituents at different positions of the
aromatic or heteroaromatic rings, have been synthesized by Ru-catalyzed
oxidative coupling of a broad range of benzylamines or heterocycles
with internal alkynes. All benzylamines and heterocycles have unprotected
primary amines as efficient directing groups
Influence of Temperature and Pressure on Cyclic Carbonate Synthesis Catalyzed by Bimetallic Aluminum Complexes and Application to Overall <i>syn</i>-Bis-hydroxylation of Alkenes
The effect of moderate temperatures (22â100 °C)
and
pressures (1â10 bar) on the synthesis of cyclic carbonates
from epoxides and carbon dioxide catalyzed by a combination of bimetallic
aluminum complexes and tetrabutylammonium bromide is investigated.
The combined bimetallic complex and tetrabutylammonium bromide catalyst
system is shown to be an order of magnitude more active than the use
of tetrabutylammonium bromide alone at all temperatures and pressures
studied. At the higher temperatures and pressures used, disubstituted
epoxides become substrates for the reaction and it is shown that reactions
proceed with retention of the epoxide stereochemistry. This allowed
a route for the overall <i>syn-</i>bis-hydroxylation of
alkenes to be developed without the use of hazardous metal based reagents.
At higher pressures it is also possible to use compressed air as the
carbon dioxide source
Cycloaurated Phosphinothioic Amide Complex as a Precursor of Gold(I) Nanoparticles: Efficient Catalysts for A<sup>3</sup> Synthesis of Propargylamines under Solvent-Free Conditions
A C,S-cycloaurated complex based
on an ortho-substituted phosphinothioic
amide framework has been synthesized in high yield through tinÂ(IV)âAuÂ(III)
transmetalation from the corresponding chlorodimethylstannyl derivative.
The latter was prepared in a two-step process involving directed ortho
lithiation/quenching with Me<sub>3</sub>SnCl followed by Me/Cl exchange.
The tinÂ(IV) and goldÂ(III) complexes have been characterized in solution
and in the solid state. In both complexes, the phosphinothioic amide
moiety acts as a CâCâPâS pincer ligand with formation
of five-membered-ring metalacycles. The use of the goldÂ(III) complex
in the amineâaldehydeâalkyne (A<sup>3</sup>) three-component
coupling synthesis of propargylamines showed that the compound is
transformed into the Sonogashira-type <i>o</i>-alkynylphosphinothioic
amide with generation of AuÂ(I) nanoparticles with an average size
of around 7 nm. These nanoparticles proved to be excellent catalysts
in A<sup>3</sup> coupling processes, providing propargylamines in
high yields under solvent-free conditions with loadings as low as
0.1 mol % and without the use of additives