TY - JOUR
T1 - A new step towards solid base catalysis
T2 - Azidoproazaphosphatranes immobilized in nanopores of mesoporous silica
AU - Raytchev, Pascal Dimitrov
AU - Bendjeriou-Sedjerari, Anissa
AU - Dutasta, Jean Pierre
AU - Martinez, Alexandre
AU - Dufaud, Véronique
PY - 2011/8/1
Y1 - 2011/8/1
N2 - Heterogeneous basic catalysts derived from proazaphosphatranes, known as Verkade's superbases, were prepared for the first time by covalent immobilization onto SBA-15 silica. In order to introduce the tether to the surface, three siloxane-containing azido derivatives of the proazaphosphatranes were first synthesized (2a-c) which after post-synthetic grafting onto silica support led to the formation of hybrid materials of different basicity and steric properties, 2a-c@SBA-15. These latter were fully characterized using a wide variety of molecular and solid-state techniques to determine their structural and textural properties. These new solid base catalysts were then evaluated in the Diels-Alder reactions of anthrone and 3-hydroxy-2-pyrone with two electron-deficient dienophiles, N-methylmaleimide and dimethyl fumarate. In general, high activity and selectivity were obtained depending on the catalytic species, the performance decreasing in the order methoxybenzyl>neopentyl> methyl azidophosphatrane. Catalyst recycling was studied for the best catalyst, the methoxybenzyl derivative, 2c@SBA-15, and it was shown that the catalyst could be re-used up to 3 cycles before any loss of activity could be detected.
AB - Heterogeneous basic catalysts derived from proazaphosphatranes, known as Verkade's superbases, were prepared for the first time by covalent immobilization onto SBA-15 silica. In order to introduce the tether to the surface, three siloxane-containing azido derivatives of the proazaphosphatranes were first synthesized (2a-c) which after post-synthetic grafting onto silica support led to the formation of hybrid materials of different basicity and steric properties, 2a-c@SBA-15. These latter were fully characterized using a wide variety of molecular and solid-state techniques to determine their structural and textural properties. These new solid base catalysts were then evaluated in the Diels-Alder reactions of anthrone and 3-hydroxy-2-pyrone with two electron-deficient dienophiles, N-methylmaleimide and dimethyl fumarate. In general, high activity and selectivity were obtained depending on the catalytic species, the performance decreasing in the order methoxybenzyl>neopentyl> methyl azidophosphatrane. Catalyst recycling was studied for the best catalyst, the methoxybenzyl derivative, 2c@SBA-15, and it was shown that the catalyst could be re-used up to 3 cycles before any loss of activity could be detected.
KW - Diels-Alder reaction
KW - hybrid materials
KW - mesoporous silica
KW - non-ionic bases
KW - organocatalysis
KW - proazaphosphatranes
UR - http://www.scopus.com/inward/record.url?scp=80051971600&partnerID=8YFLogxK
U2 - 10.1002/adsc.201100270
DO - 10.1002/adsc.201100270
M3 - Article
AN - SCOPUS:80051971600
VL - 353
SP - 2067
EP - 2077
JO - Advanced Synthesis and Catalysis
JF - Advanced Synthesis and Catalysis
SN - 1615-4150
IS - 11-12
ER -