This sulfone allowed the preparation of Z-fluoroalkenoates with very high stereoselectivity from both aromatic and aliphatic aldehydes. The nature of the heterocycle on the course of the Julia–Kocienskireaction is discussed.
first time. The reaction is stereospecific and provides fair to quantitative yields of fluoroalkenes. The Mizoroki–Heck reaction starting from more hindered and usually reluctant trisubstituted acrylate, to access tetrasubstituted fluoroalkenes, is also reported. Finally, the use of a three-step synthesis sequence, including Mizoroki–Heck reaction, allows the synthesis of fluorinated analogues of therapeutic
E-selectivity was observed in the Horner-Wadsworth-Emmons (HWE) reactions of ethyl 2-fluoro-2-diethylphosphonoacetate 1 with alkyl aryl ketones 2a-f using Sn(OSO2CF3)2 and N-ethylpiperidine. Mg(II)-promoted HWE reactions of 1 with aldehydes 2h,i afforded α-fluoro-α,β-unsaturated esters 3h,i in a Z-selective manner depending on the reaction temperatures.
The synthesis of α-fluoroacrylates and α-bromo-α-fluoroalkenes was achieved in very good yields using aldehydes and ketones, triphenylphosphine, diethylzinc as promoter, and ethyl dibromofluoroacetate or dibromofluoromethane, respectively. A change in the addition sequence was critical in order to obtain exclusively α-fluoroacrylates in good yields.
In this manuscript, a simple and efficient sulfa-Michael addition reaction of aryl thiols to trisubstituted α-fluoro-α,β-unsaturated esters both in racemic and, for the first time, in enantioselective version is reported. The commercially available dimer of cinchona derivatives (DHQ)2PYR was used as a catalyst. This strategy showed a great tolerance for various substrates and substituents, providing