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| Author(s): |
Fernanda Ferraz Camilo
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 1998-03-19 |
| Examining board members: |
Jonas Gruber;
Marden Antônio de Alvarenga;
Timothy John Brocksom
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| Advisor: | Jonas Gruber |
| Abstract | |
The aim of this work is to study Diels-Alder reactions of methyl thiocinnamates, substituted at the para position by electron-donating and electron-withdrawing groups, as well as their corresponding ester analogues, towards cyclopentadiene in the presence of Lewis acid catalysts. Several Lewis acids, such as Ti(OBu-n)4, ZnCI2, BF3·OEt2, TiCl4, AICl3 boroncatechol bromide and BBr3, which are usually employed in Diels-Alder reactions, were tested. Only boroncatechol bromide led to the expected adducts with total stereoselectivity in almost all cases. The use of water or a 5 mol·L<SUP-1 ethereal solution of lithium perchlorate did not give good results. We believe the results obtained by the use of boroncatechol bromide are due to the strong complexation of the dienophile carbonyl oxygen with the boron atom, which has been confirmed by 1H NMR, and to secondary interactions. The cathodic reduction of the above thiocinnamates is also presented. The electrolyses, carried out potentiostatically in a polar aprotic solvent, led exclusively to the trans-trans cyclic hydrodimers in good yields. (AU) | |