Synthesis of Fluorinated exo‐Glycals through Modified Julia Olefination

Abstract

An efficient synthesis of fluorinated enol ethers derived from carbohydrates is reported. A modified Julia olefination reaction of functionalized lactones with fluorine‐substituted sulfones gives the corresponding monofluorinated tri‐ or tetrasubstituted exo‐glycals.

Synthesis of Fluorine‐Containing 3,3‐Disubstituted Oxetanes and Alkylidene Oxetanes

“…To access vinyl sulfones to act as Michael acceptors, a HornerWadsworth-Emmons reaction was realized with phosphonosulfone 4 in the presence of NEt 3 and LiCl in tetrahydrofuran (THF) at 20°C. [36] The reaction of sulfone 4 with oxetanone 5 led to corresponding vinyl sulfone 5e in 84 % yield. Similar results were obtained with N-Boc-3-azetidinone 6 and cyclobutanone 7, and vinyl sulfones 6e and 7e were obtained in 96 and 71 % yields, respectively.…”

“…The use of substituted ketones is rare because competitive reactions occur with substituted ketones. [32,33] With a different route to π-deficient heterocyclic fluorosulfones on hand, [32][33][34][35][36] investigation and prep-the Julia-Kocienski reaction performed with sulfones 1 and 2 afforded corresponding oxetanes 5a-5c in 50-94 % yields. With sulfone 3 the reaction reached completion after 3 h at 20°C, and crude 5d ( 19 F NMR: -118.9 ppm, triplet of quintet, 18.4 and 3.4 Hz) was unstable.…”

Synthesis of Monofluoroalkenes: A Leap Forward

“…Gueyrard and co-workers examined the synthesis of fluorinated exo-glycals through the Julia-Kocienski olefination. 71 To do so, the reaction was performed between a lactone and benzothiazol-2-yl fluoromethyl sulfone; using benzyl-protected pyranose and furanose derivatives gave exocyclic monofluoroalkenes in good yields (Scheme 51). It is also possible to perform the reaction using silylated protecting groups, such as TES or TBDMS, and acetal as protecting group, with similar yields and stereoselectivity.…”

Synthesis of Fluorinated and Trifluoromethyl-Substituted Alkenes through the Modified Julia Olefination: An Update

“…The synthesis of tri-and tetrasubstituted fluorinated exocyclic enol ethers from lactones via a modified Julia reaction has been developed (Scheme 15). 26 Benzyl and silyl ethers and isopropylidene groups are tolerated on the lactone. In the case of triethylsilyl ethers, better yields are obtained in the absence of a Lewis acid.…”