Regioselective reductive openings of 4,6-benzylidene acetals: synthetic and mechanistic aspects.
Författare
Summary, in English
The use of benzylidene acetals as protecting groups in carbohydrate chemistry is utterly important. The main advantage of benzylidene acetal is the ability for regioselective openings. 4,6-benzylidene acetal can be opened selectively under reductive conditions to yield either free 4-OH or 6-OH. There are a plethora of methods available for regioselective openings, but only a few of these are widely used. In recent years, the mechanism has been investigated for borane mediated openings and it seems likely that the regioselectivity is determined by borane, rather than Lewis acid. When borane is activated by Lewis acids, borane is the most electrophilic species that consequently coordinates to the most nucleophilic oxygen of the acetals, usually O-6. This results in the formation of 6-O-benzyl ethers. If borane is not activated, Lewis acid is the most electrophilic species that thus adds to O-6 and hence generates the 4-O-benzyl ether.
Avdelning/ar
Publiceringsår
2011
Språk
Engelska
Sidor
1358-1370
Publikation/Tidskrift/Serie
Carbohydrate Research
Volym
346
Dokumenttyp
Artikel i tidskrift
Förlag
Elsevier
Ämne
- Organic Chemistry
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 1873-426X