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Optimization of Ring‐Closing Metathesis: Inert Gas Sparging and Microwave Irradiation
Author(s) -
Nosse Bernd,
Schall Andreas,
Jeong Won Boo,
Reiser Oliver
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200505137
Subject(s) - sparging , chemistry , inert gas , ring closing metathesis , microwave irradiation , salt metathesis reaction , microwave , metathesis , irradiation , photochemistry , inert , catalysis , chemical engineering , organic chemistry , nuclear physics , polymerization , physics , quantum mechanics , engineering , polymer
A systematic study of a ring‐closing metathesis towards a tetrasubstituted double bond as part of a seven‐membered ring in a 5.7.5‐tricyclic guaianolide system is described. By combining two techniques, namely sparging an inert gas through the solution together with dielectric heating via microwave irradiation a high‐yielding ring‐closing metathesis reaction in this particularly challenging case was achieved. The results obtained compare favorably with conventional heating conditions or with microwave irradiation in a closed system. The key aspects seem to be that rapid microwave irradiation diminishes catalyst decay by allowing the required high reaction temperature to be reached quickly and homogeneously and thereby providing enough energy for a successful metathesis reaction, while inert gas sparging is purging off evolving ethylene to shift the equilibrium to the product.