Hydrogen fluoride pyridine complex

There is continuous interest in cleavage of epoxides as a general method lor the preparation of fluorohydrins Epoxides are effectively cleaved under mild conditions by a 70% hydrogen fluoride-pyridine complex (Olah s reagent). The... 

Table 1. Cleavage of Glycidic Esters, Glycidic Amides, and Glycidic Nitriles by Hydrogen Fluoride-Pyridine Complex 110,11]...

The noteworthy advantages of the allyl ester are (a) it is readily introduced into amino acids (b) after isomerization (to 1-propenyl) by a palladium(O) catalyst it may be removed under weakly acidic or basic and neural conditions (32), even if sulfur-containing amino acids are present (34) (c) it shows orthogonal stability to the tert-butyloxycarbonyl and 9-fluorenylmethoxy-carbonyl groups (10) and (d) it is not affected by the hydrogen fluoride-pyridine complex (35). 

X0 esters in the 2-position, but is not sufficiently reactive to fluorinate ketones. jl-Oxo esters are selectively fluorinated at the a-position by iodotoluene difluoride and a hydrogen fluoride pyridine complex. " ... 

Bicyclic aziridines 17 with a l-azabicyclo[n.l, 0]alkane framework can also be subjected to ring opening with either hydrogen fluoride or the hydrogen fluoride-pyridine complex to give 3-fluoro-l-azacycloalkanes 18. ° ° ... 

The simultaneous addition of fluorine and bromine to alkynes can be carried out by the use of bromine fluoride, prepared directly from the corresponding elements, the hydrogen fluoride/IV-bromoacetamide system (HF/AcNHBr) or the hydrogen fluoride/pyridine complex in combination with either (V-bromosuccinimide or 1,3-dibromo-5.5-dimethylhydanloin (DBH). Examples arc listed in Tabic 44. 

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