[65325-68-0] · C7H7FOS · Fluoromethyl Phenyl Sulfoxide · (MW 158.21)
Physical Data: bp 75 °C/0.3 mmHg; n
Solubility: sol THF, CH2Cl2, CHCl3.
Preparative Methods: by the oxidation of Fluoromethyl Phenyl Sulfide with either N-Bromosuccinimide or m-Chloroperbenzoic Acid (eq 1).1c-f Studies of the structure of fluoro(phenylsulfinyl)methyllithium, investigated by NMR, suggest that lithium is bound to oxygen, rather than to the a-carbon atom.5
Purification: pure compound is obtained either by distillation or column chromatography on silica using hexane-ethyl acetate (1:4).
Handling, Storage, and Precautions: use in a fume hood.
The reaction of fluoro(phenylsulfinyl)methyllithium, generated with Lithium Diisopropylamide, with aldehydes gives the corresponding a-fluoro-b-hydroxy sulfoxides, which upon pyrolysis give fluoromethyl ketones (eq 2).1b,2
a-Fluoro-1,3-keto sulfoxides, prepared from the addition of alkylated a-fluoromethyl phenyl sulfoxide carbanion to aldehydes followed by Swern oxidation (Dimethyl Sulfoxide-Oxalyl Chloride), undergo desulfinylation with Ethylmagnesium Bromide to give a-fluoro ketones (eq 3).6 Pyrolysis of the a-fluoro-1,3-keto sulfoxides gives a-fluoro-a,b-unsaturated ketones (eq 3).6 Dienones can be prepared by this procedure and the product undergoes the Nazarov cyclization to give 2-fluoro-2-cyclopenten-1-one (eq 4).6b
Fluoro(phenylsulfinyl)methyllithium can be alkylated with alkyl iodides or reactive alkyl bromides to give monoalkylated products which upon pyrolysis afford vinyl fluorides (eq 5).2 The addition of the a-fluoromethyl-N-methyl(phenyl)sulfoximine carbanion, derived from a-fluoromethyl phenyl sulfoxide, to carbonyl compounds gives a-fluoro-b-hydroxy(phenyl)sulfoximine adducts, which upon reductive desulfinylation with Aluminum Amalgam yield fluoroalkenes (eqs 6 and 7).3c
a-Substituted a-fluoro phenyl sulfoxides, prepared from thioacetals (eq 8)3b or from the corresponding sulfoxides, are used in the synthesis of fluoroalkenes (eqs 9 and 10).3d,7
Fluoro(phenylsulfinyl)methyllithium adds to aryl imines to give phenylsulfinylaziridines as a mixture of isomers (eq 11). This method is complementary to the reaction employing chloro(phenylsulfinyl)methyllithium.4
Vichai Reutrakul & Manat Pohmakotr
Mahidol University, Bangkok, Thailand