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Can acyclic conformational control be achieved via a sulfur-fluorine gauche effect?

ABSTRACT: The gauche conformation of the 1,2-difluoroethane motif is known to involve stabilising hyperconjugative interactions between donor (bonding, ?_C-H) and acceptor (antibonding, ?*C-F) orbitals. This model rationalises the generic conformational preference of F-C_?-C_?-X systems (?_FCCX ? 60°), where X is an electron deficient substituent containing a Period 2 atom. Little is known about the corresponding Period 3 systems, such as sulfur and phosphorus, where multiple oxidation states are possible. Conformational analyses of ?-fluorosulfides, -sulfoxides and -sulfones are disclosed here, thus extending the scope of the fluorine gauche effect to the 3rd Period (F-C-C-S(O) _n ; ?_FCCS ? 60°). Synergy between experiment and computation has revealed that the gauche effect is only pronounced in structures bearing an electropositive vicinal sulfur atom (S⁺-O^-, SO₂).

SUBMITTER: Thiehoff C

PROVIDER: S-EPMC5659174 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Can acyclic conformational control be achieved via a sulfur-fluorine gauche effect?

Thiehoff C C Holland M C MC Daniliuc C C Houk K N KN Gilmour R R

Chemical science 20150417 6

The gauche conformation of the 1,2-difluoroethane motif is known to involve stabilising hyperconjugative interactions between donor (bonding, σC-H) and acceptor (antibonding, σ*C-F) orbitals. This model rationalises the generic conformational preference of F-Cβ-Cα-X systems (φFCCX ≈ 60°), where X is an electron deficient substituent containing a Period 2 atom. Little is known about the corresponding Period 3 systems, such as ...[more]

PMID: 29511517

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