Special Issue "Microwave Assisted Synthesis"

Guest Editor
Dr. Julio A. Seijas Vázquez
Departamento de Química Orgánica, Universidad de Santiago de Compostela, Facultad de Ciencias-Campus de Lugo, Alfonso X el Sabio, 27002 Lugo, Spain
Website: http://www.usc.es/orchemlu/
E-Mail:
Interests: synthesis of compounds with biologic activity; synthesis of compounds with interest for agro-food field; solation, estructural determination and synthesis of natural products; microwave organic reactions enhancement

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Manuscript ID: molecules-micrasyn-01-it-Brusotti
Type of Paper: Article
Title: Experimental Design Methodology applied to a Microwave assisted Synthesis of a fragrant Compound: Calone 1951^®
Authors: Gloria Brusotti ^1,*, Sandra Furlanetto ²,Carmela De Risi ³,Marco Carando ⁴,Giorgio Marrubini ¹,Carlo Gandini ¹,Gabriella Massolini¹
Affiliations: ¹Department of Pharmaceutical Chemistry, Pavia University, viale Taramelli12, 27100 Pavia,Italy
²Department of Pharmaceutical Science, Florence University, Via U. Schiff 6, 50019 Sesto F.no (FI), Italy
³ Department of Pharmaceutical Science, Via Fossato di Mortara, 17-19, 44100 Ferrara, Italy
⁴ Osmotech Srl, viale Taramelli12, 27100 Pavia,Italy
^* Author to whom correspondence should be addressed; E-mail: gloria.brusotti@unpv.it
Abstract: The first application of experimental design methodology to the microwave assisted organic synthesis (MAOS) is here described for the synthesis of 7-methyl-benzo[b][1,4]dioxepin-3-one 1, or Calone 1951^®, chosen as target compound. The industrial synthesis involves a three steps sequence: Williamson reaction, Dieckmann condensation and acid hydrolysis/decarboxylation. Starting from an European patent we aimed at synthesising 1 reducing the reaction time and the number of steps: the reaction of 4-methyl catechol with dichloroacetone was investigated using microwave heating instead of conventional heating while a widely applicable multivariate approach of experimental design was applied to maximize the synthesis yield and to reduce the number of experiments.
A 12-run D-optimal asymmetrical screening matrix (2²1⁴//12) allowed us toidentify, among different factors, those which really had an influence on the response. A response surface study, carried out in the experimental domain defined by temperature and time, pointed out the best reaction conditions.
Applying microwave heating the reaction can be carried out in one step reducing the time from 6 h to 18 min. and increasing the yield from 56% to 70.5%.
Calone 1951^® was determined and characterized by gas chromatography-mass spectrometry (GC-MSD), gas chromatography with Flame Ionization Detector (GC-FID) and ¹H-NMR analysis.
Keywords: Experimental design/Fragrances/Microwaves irradiation