Alkyl Orthoester

Scheme 5.5 1,2-O-Alkyl orthoesters in glycosylation (a) polar or nonpolar solvents, high amount of acid (b) low polarity solvents, minor amounts of acid catalyst. 

O-Alkyl Orthoesters as Clycosyl Donors - Early Developments... 

While the chlorides of strongly electropositive elements such as thorium, lanthanides, and some later 3d metals form adducts with alcohols (57), anhydrous chlorides of boron (6) and silicon (9) form the corresponding alkoxides or alkyl orthoesters, B(OR)3 and Si(OR)4, with primary and secondary alcohols. The reactions of tertiary alcohols are complicated by the facile side formation of tertiary alkyl chloride and water by the reaction between tertiary alcohols... 

L.A.Pavlova, Y.A.Davidovich and S.V.Rogozhin, Alkyl Orthoesters and their Applications in Organic Synthesis, Russ.Chem.Rev.,... 

The preparation and biological properties of 17,21-alkyl orthoesters, 17-mono-esters, and 17,21-diesters of 6a,9a-difluorocortisol and 6,9-difluoroprednisolone have been reported. ... 

In the field of reactions of thioglycosides the photobromination of phenylthio compounds has been covered in a review. As has been noted before, and has been used usefully in synthesis of 2-deoxy compounds, the alkylthio group of thioglycosides may migrate to C-2 under certain conditions. Thus, as well as compound 93 giving the expected 2,3-orthoester on treatment with alkyl orthoesters in acid conditions, it gave compound 94... 

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