| Autor: |
Mati Karelson, Kostyantyn Kirichenko, Peter J. Steel, Alan R. Katritzky, Yu Ji |
| Rok vydání: |
2003 |
| Předmět: |
|
| Zdroj: |
ARKIVOC, Vol 2003, Iss 6, Pp 49-61 (2003) |
| ISSN: |
1551-7012 |
| DOI: |
10.3998/ark.5550190.0004.607 |
| Popis: |
Reactions of 2-hydroxyphenylmethanones 8 with 1-chloro-1-(benzotriazol-1-yl)alkanes 9 give intermediates 10a-h , which were converted by trimethylsulfonium iodide to oxirans 11a-h. Treatment of 11a-h with LDA gave either 3-hydroxymethyl-2,3-dihydrobenzofurans or 3- hydroxymethylbenzofurans depending on substituents. Benzofurans undergo electrophilic substitution at the 2-position, and this normally precludes the direct introduction of a 3-substituent. Available methods for the preparation of 3- hydroxymethylbenzofurans 1 include (i) ring syntheses which often involve multi-step reactions, 5,7 e.g. via benzofuran-2,3-dicarboxylic acid 2; (ii) Pd-catalyzed heteroannulation of 2- iodophenols 3 with O-silyl protected alkynols, 8 or from 3-(2-bromophenoxy)acrylic ester 4; 3 (iii) cyclization of 1-(2-(2-propynyloxy)phenyl)diazonium salts 5; 9 (iv) reaction of O-silyl protected 2-ethynylphenols 6 with aldehydes under TBAF catalysis; 10 (v) oxidation of 3- methylbenzofurans 7 with selenium dioxide followed by reduction with LAH; 11 and (vi) |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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