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Chemistry. 2018 Feb 6;24(8):1838-1843. doi: 10.1002/chem.201704807. Epub 2017 Dec 11.

On Pentakis(pentafluoroethyl)stannate, [Sn(C2 F5 )5 ]- , and the Gas-Free Generation of Pentafluoroethyllithium, LiC2 F5.

Author information

1
Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany.

Abstract

Pentafluoroethyllithium, LiC2 F5 , has been established as an efficient and versatile reagent for the transfer of the pentafluoroethyl unit to a number of electrophiles. Here, the stability of this species up to -40 °C is of advantage, particularly in comparison to its smaller congener LiCF3 . The usual production of LiC2 F5 , however, from gaseous HC2 F5 or IC2 F5 and strong bases requires specially designed apparatuses, which severely impeded its value as a laboratory reagent. In this contribution we communicate an alternative gas-free and highly efficient protocol for the synthesis of LiC2 F5 from the already commercialized stannate salt [PPh4 ][Sn(C2 F5 )5 ]. The [Sn(C2 F5 )5 ]- anion represents not only the first example of a structurally characterized hypervalent pentaalkylstannate but also serves as a precursor for the synthesis of the homoleptic tetrakis(pentafluoroethyl)stannane, Sn(C2 F5 )4 . The reaction of the latter with n-butyllithium provides an insight into the mechanism of LiC2 F5 generation.

KEYWORDS:

fluorine; gas-free; lithium; perfluoroalkylation; tin-lithium exchange

PMID:
29068093
DOI:
10.1002/chem.201704807

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