Protecting groups tetrahydrofuranyl

Tetrahydropyranyl (TUP) and tetrahydrofuranyl ethers are important protecting groups for alcohols and phenols in organic synthesis, but they can also be converted to other useful functional groups [8, 118]. For example, allylation of a TUP ether should yield a highly functionalized molecule (Scheme 15). 

Tetrahydrofuranyl derivatives of uridine and 2 -deoxycytidine, either partially or completely O- and/or N-substituted, have been prepared from the nucleoside with dihydrofuran. The protecting group may be removed either by dilute acid or by treatment with microsomal non-specific oxidases. 3 -0-tetrahydrofuranyl-N-benzoyladenosine and a 5 -0-dimethoxytrityl-arabinosyl-adenine derivative have been prepared conventionally for use in ribo-oiigonucieotide synthesis. 

Tetrahydrofuranyl (THF) ethers are reported to be useful alternatives to tetrahydropyranyl (THP) ethers for the protection of alcohols (and thiols). THF ethers are easily formed, and are more sensitive to acidic hydrolysis than are THP ethers. We are warned that hydroboration-oxidation or peracid oxidation of simple unsaturated compounds containing a hydroxy-group protected as its THP ether has led to violent detonations. The danger comes from the ready formation of peroxides from THP ethers, and presumably also from THF ethers these peroxides, though very sensitive, are not easily removed by ordinary chemical methods. 

Iwai S, Yamada E, Asaka M, Hayase Y, Inoue H, Ohtsuka E. A new solid-phase synthesis of oligoribonucleotides by the phosphoro-p-anisidate method using tetrahydrofuranyl protection of 2 -hydroxyl groups. Nucleic Acids Res 15 3761-3772, 1987. 

Ketone 64 has been synthesized from D-xylose and used to construct the tetrahydrofuranyl calcheamicin analogue 65. Last year, Reet described a synthesis of muscarine from L-rhamnose and this has now been extended to (3R)-hydroxymuscarine 66 (tosylate salt). Both syntheses (and full details of the muscarine work have also appeared) proceed without the necessity of functional group protection. 

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