Synthesis and Application of Versatile Monofluoro Building Blocks by Manipulation of the Multifunctional Carbon Compounds.

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Development of versatile and practical building blocks for aliphatic monofluoro compounds was attempted in light of recent increasing interest and demand for both new materials and bioactive molecules. Our synthetic approach involves the utilization of the multifunctional carbon compounds and the convenient direct fluorination method which were recently developed in our laboratory. Results are summarized as follows;1. Alkylation follwed by selective fluorination of commercially available nitroacetates produced 2-fluoro-2-nitroalkanoic esters(5), the first fluorine-containing building blocks. The usefulness of 1 was demonstrated by converting into various monofluoro derivatives. Selective denitration of 1 gave 2-fluoroalkanoic esters(2)m which were further converted into the corresponding 2-fluoroalkanoic acids and 2-fluoroalkanols. On the other hand, dealkoxycarbonylation of 1 yielde fluoronitroalkanes, into which the second alkyl groups were introduced to give the di-alkylated fluoron … More itromethanes(3). denitration of 3 afforded successfully fluoroalkanes and fluoroalkenes, which have aingle fluorine atom on the alkyl chains dependent on the choice of teh two alkyl groups.2. Denitrative introduction of the third alkyl groups into 3 was attempted to produce the tertiary alkyl fluorides although in low yields, which are the most difficult structures to prepare among the various organofluorine compounds. On the other hand, denitrative alkylation of 1 gave the target compounds in high yields. We have thus developed versatile building blocks equivalent to the synthon of monofluoromethylene dicarbanion.3. 1-Benzenesulfonyl-1-fluoro-1-nitroalkanes(4), 2-benzenesulfonyl-2-fluoroalkanoic esters(5), and 1-benzenesulfonyl-1-fluorophoalkylphosphonates(6) were also prepared from the corresponding difunctional carbon compounds. Removal of the functional groups of 4 and 5 failed. However, reaction of 6 with various carbonyl compounds produced fluorovinylsulfone derivatives(7). Which were further transformed into various monofluoro compounds via michael addition, diels-alder reaction, and 1,3-dipolar cycloaddition. Less