7.4 Simultaneous US/MW-Promoted Organic Syntheses
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Scheme 7.3 Schematic representation of epoxide opening under SMUI
Scheme 7.4 Schematic representation of Wittig reaction and hydrolysis
Another example of SMUI use in organic synthesis is the search for new methodologies for highly regio- and stereo-selective epoxide cleavage by nucleophiles in
aqueous media. A comparison of reaction conditions (conventional and MW alone
at 50 °C, US alone at 45 °C, and SMUI at 45 °C) led to the finding that simultaneous
irradiation provided extremely fast and regioselective epoxide opening with NaN 3
and that water media did not compete with the nucleophile (Scheme 7.3).
The Wittig olefination, using polymer-bound triphenylphosphine (TPPP), has
been optimized under combined US–MW irradiation and in a tandem procedure
made up of a Wittig reaction and the hydrolysis of the ester intermediates to obtain
α,β-unsaturated carboxylic acids (Rossi et al. 2009) (Scheme 7.4).
105
Scheme 7.3 Schematic representation of epoxide opening under SMUI
Scheme 7.4 Schematic representation of Wittig reaction and hydrolysis
Another example of SMUI use in organic synthesis is the search for new methodologies for highly regio- and stereo-selective epoxide cleavage by nucleophiles in
aqueous media. A comparison of reaction conditions (conventional and MW alone
at 50 °C, US alone at 45 °C, and SMUI at 45 °C) led to the finding that simultaneous
irradiation provided extremely fast and regioselective epoxide opening with NaN 3
and that water media did not compete with the nucleophile (Scheme 7.3).
The Wittig olefination, using polymer-bound triphenylphosphine (TPPP), has
been optimized under combined US–MW irradiation and in a tandem procedure
made up of a Wittig reaction and the hydrolysis of the ester intermediates to obtain
α,β-unsaturated carboxylic acids (Rossi et al. 2009) (Scheme 7.4).