Synthesis of difluorocyclopropyl carbocyclic homo-nucleosides

Synthesis and HPLC-Analysis of N-(2-Phenyl-cyclopropyl)-Substituted Chain Elongated Nucleoside Analogues

“…M itsunobu reaction [9,10] of (± )-6 in the pres ence of adenine, triphenylphosphane (TPP) and diethyl azodicarboxylate (D E A D ) gave the ade nine analogue (±)-7; under similar conditions from (± )-6 in the presence of N3-benzoylthymine [10] the protected thymine analogue (± )-8 was ob tained. D eprotection of (± )-8 with aqueous am monium hydroxide gave the target compound (±)-9.…”

“…D eprotection of (± )-8 with aqueous am monium hydroxide gave the target compound (±)-9. In an analogous m anner from (± )-6 and N3-benzoyluracil [10] (±)-10 was obtained which gave upon deprotection with ammonium hydroxide the cyclopropanoid uracil derivative ( ± ) -ll.…”

Trimethylsilyl fluorosulfonyldifluoroacetate (TFDA): a new, highly efficient difluorocarbene reagent

“…The main practical problem associated with this difluorocyclopropanation procedure is the requirement that large excesses of Na þ -O 2 CCF 2 Cl must be used in order to obtain decent yields when using less-reactive substrates. (Note the 11 equivalents used in the example that is provided) [8].…”

Recent advances in the synthesis of fluorinated nucleosides

“…350 Besides the aforementioned monofluorinated cyclopropane nucleosides, Zemlicka's group and the Csuk group also carried out the synthesis of a series of difluorocyclopropyl carbocyclic nucleosides 993, starting from the (Z)-2-butenyl derivatives 990 (Scheme 147). 351,352 As the key step of their synthesis, conversion of 990 into the 2,2-difluorocyclopropylmethanol 991 was realized by means of difluorocyclopropanation with ClCF 2 CCO 2 Na in diglyme at 180-190 C followed by deacetylation or debenzoylation. At this stage, two methods were utilized to introduce the nucleic bases.…”