Preparation and Reactivity of Tris(trifluoromethylselanyl)carbenium [(CF3Se)3C+] and Trifluoromethylsulfanylacetic Acid Derivatives [(CF3S)3–nCXn(O)R]

✍ Scribed by Haas, Alois ;Möller, Guido

• Publisher: Wiley (John Wiley & Sons)
• Year: 1996
• Tongue: English
• Weight: 673 KB
• Volume: 129
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19961291112

✦ Synopsis

Abstract

Reaction pathways for the synthesis of the (CF~3~E)~3~C moieties (E = Se, S) are described. [(CF~3~Se)~3~C^+^][AsF] was found to be a suitable synthon for the preparation of (CF~3~Se)~3~C derivatives. It can be prepared either from (CF~3~Se)~3~C derivatives. It can be prepared either from (CF~3~Se)~4~C or (CF~3~Se)~3~CF and AsF~5~ in liquid SO~2~. Direct access to (CF~3~Se)~3~CF was realized by the reaction of FCBr~3~ with Hg(SeCF~3~)~2~. Treatment of [(CF~3~Se)~3~C^+^][AsF~6~^‐^] with potassium halides provided (CF~3~Se)~3~CX (X = F, Cl, Br). A different course took the reaction with KI, as CF~3~SeSeCF~3~ and (CF~3~Se)~2~C=C(SeCF~3~)~2~ were formed as main products. Minor amounts of (CF~3~Se)~3~CC(SeCF~3~)~3~ were formed which could be isolated and unambiguously characterized. Only two routes led to a threefold CF~3~S‐substituted acetic acid ester (CF~3~S)~3~CC(O)OR [R = CH~3~, (CH~3~)~3~C]: Metatheses between (CF~3~S)~2~CBrC(O)OCH~3~ and Hg(SCF~3~)~2~ and metalation of (CF~3~S)~2~CHC(O)OR [R = CH~3~, (CH~3~)~3~C] with NaH followed by reaction with CF~3~SCl. Other precursors such as (CF~3~S)~2~CXC(O)OR′ [X = H, Br; R′ = Me~3~Si, (n‐C~4~H~9~)~3~Sn] and (CF~3~S)~2~CBrC(O) Y (Y = Cl, Br) were synthesized but could not be converted to the corresponding (CF~3~S)~3~C derivatives. Attempts to hydrolyze (CF~3~S)~3~CC(O)OR to (CF~3~S)~3~CC(O)OH failed.