Abstract
3-Aminopropyl functionalised silica gel may be readily transformed into a stable immobilised
palladium catalyst. This catalyst was then successfully employed in a series of fast,
copper-free Sonogashira coupling reactions.
Key words
silica - palladium - catalyst - copper-free cross-coupling - Sonogashira - aryl iodides
References
<A NAME="RD30704ST-1">1 </A>
Kirschnig A.
Monenschein H.
Wittenberg R.
Angew. Chem. Int. Ed.
2001,
40:
650
<A NAME="RD30704ST-2">2 </A>
Clapham B.
Reger TS.
Janda KD.
Tetrahedron
2001,
57:
4637
<A NAME="RD30704ST-3">3 </A>
Uozumi Y.
Nakai Y.
Org. Lett.
2002,
4:
2997
<A NAME="RD30704ST-4">4 </A>
Miyaura N.
Suzuki A.
Chem. Rev.
1995,
95:
2457
<A NAME="RD30704ST-5">5 </A>
Gonthier E.
Breinbauer R.
Synlett
2003,
1049
6a </A>
Sonogashira K.
J. Organomet. Chem.
2002,
653:
46
6b </A>
Rossi R.
Carpita A.
Bellina F.
Org. Prep. Proced. Int.
1995,
129
<A NAME="RD30704ST-7">7 </A>
Neckars DC.
J. Chem. Educ.
1975,
52:
695
<A NAME="RD30704ST-8">8 </A>
Lin C.-A.
Luo F.-T.
Tetrahedron Lett.
2003,
44:
7565
<A NAME="RD30704ST-9">9 </A>
Brase S.
Gil C.
Knepper K.
Bioorg. Med. Chem.
2002,
10:
2415
<A NAME="RD30704ST-10">10 </A>
Siemsen P.
Livingstone RC.
Diederich F.
Angew. Chem. Int. Ed.
2000,
39:
2632
<A NAME="RD30704ST-11">11 </A>
Aldrich reference 36, 425-8.
<A NAME="RD30704ST-12">12 </A>
Angeletti A.
Canepa C.
Martinetti G.
Venturello P.
J. Chem. Soc., Perkin Trans. 1
1989,
105
<A NAME="RD30704ST-13">13 </A>
Matrex Silica 60 (37-70 mesh).
<A NAME="RD30704ST-14">14 </A>
Clark JH.
Chemistry of Waste Minimisation
Chapman and Hall;
Glasgow:
1995.
<A NAME="RD30704ST-15">15 </A>
Price PM.
Clark JH.
Macquarrie DJ.
J. Chem. Soc., Dalton Trans.
2000,
101
<A NAME="RD30704ST-16">16 </A>
Clark JH.
Macquarrie DJ.
Chem. Commun.
1998,
853
17a </A>
Hallmann K.
Macedo E.
Nordstrom K.
Moberg C.
Tetrahedron: Asymmetry
1999,
10:
4037
17b </A>
Zhang TY.
Allen MJ.
Tetrahedron Lett.
1999,
40:
5813
17c </A>
Terrett NK.
Comb. Chem. Online
2003,
5:
43
<A NAME="RD30704ST-18">18 </A>
Djakovitch L.
Rollet P.
Tetrahedron Lett.
2004,
45:
1367
<A NAME="RD30704ST-19">19 </A>
These studies were conducted on a Mettler TG50 Thermogravimetric Analyser. The decomposition
weight loss was measured over the range 200-650 °C at a temperature rate increase
of 20.0 °C min-1 .
<A NAME="RD30704ST-20">20 </A>
Leadbetter NE.
Tominack BJ.
Tetrahedron Lett.
2003,
44:
8653
<A NAME="RD30704ST-21">21 </A>
Representative Experimental Procedure: the Synthesis of Diphenylacetylene.
To a small dry glass tube/flask charged with a magnetic stirrer bar, iodobenzene (0.204
g, 1.0 mmol) and phenyl-acetylene (0.102 g, 1.0 mmol) was added piperidine (0.256
g, 3.0 mmol) and catalyst 3 (0.015 g). The reaction vessel was sealed with a septum and heated to a temperature
of 70 °C on an oil bath with constant stirring. After about 10 min the contents were
cooled and decanted into a separating funnel. The residual supported catalyst was
washed with Et2 O (3 × 10 cm3 ) and the washings added to the separating funnel. Then, H2 O (20 mL) was added to the separating funnel and the organic layer was separated neutralised,
by washing with dilute HCl (15% v/v), washed with H2 O (2 × 15 mL), dried over anhyd MgSO4 and the organic solvent removed, in vacuo, to afford the crude product (0.1602 g,
90%). This was characterised by GC-MS which confirmed that the yield of diphenylacetylene
(85%), IR and NMR spectroscopy using an authentic sample for reference purposes.
<A NAME="RD30704ST-22">22 </A>
The yields of coupled products obtained from reactions involving supported palladium
catalysts are often superior to those obtained from the corresponding homogeneous
reaction.
<A NAME="RD30704ST-23">23 </A>
This work was carried out by A. Al-Saardi as part of an MChem undergraduate final
year project at Kingston University.
