Full text
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| Author(s): |
Andréa Maria Aguilar
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC) |
| Defense date: | 1998-11-13 |
| Examining board members: |
Gil Valdo Jose da Silva;
Jose Ricardo Romero;
Massami Yonashiro
|
| Advisor: | Gil Valdo Jose da Silva |
| Abstract | |
ln this work, studies concerning the synthesis of 3-substituted forans, bearing a chiral carbon, were developed. [fórmula] Several terpenoids have this structural moiety m their molecules, as illustrated by trans-crotonin (1), whose synthesis is being developed in our laboratory. [fórmula] D-manitol (11), a readily available polyhydroxylated natural compound, was selected as the starting material to give the optically active 3-substituted furan with the desired configuration. The α,β -unsaturated esters 4a and 4b were prepared from D-manitol (11) according to a published procedure. [fórmula] Michael addition of bis (phenylseleno) methyl lithium (5) to the esters 4a or 4b gave the product 6. The corresponding acid was prepared by hydrolysis of compound 6. Lactonization of the acid 7 gave compound 8. Attempts to prepare furan through DIBAL-H reduction of lactone 8 failed, probably due to the instability of the lactol. The butenolide 32 was obtained from the selenoxide fragmentation (oxidation of 8). The preparation of furans from butenolides is described in the literature. This last reaction has not been done because yield in the preparation of 32 from 8 was very low, making this method less attractive compared to the previous one developed in our laboratory. [fórmula] (AU) | |