A Convenient Synthesis of Fluorinated α,β-Ynones

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

“…This process allowed us to obtain the required ynones 2 as long as the residue R was aromatic, while with an aliphatic substituent in this position, a full conversion was not observed even after a prolonged reaction period and at a higher temperature, and such conditions seemed to evoke the degradation of the products 2 to some extent. This was not the case for the Dess–Martin periodinane oxidation and the propargylic alcohols with C 7 H 15 as the residue R 1 by Hoye et al [ 15 ] and C 9 H 19 as the residue R 1 by the Sandford group [ 21 ], who recorded 80% and 76% isolated yield, respectively, of the corresponding ketones. Because these compounds were previously isolated inconveniently by preparative GLC [ 15 ] or distillation [ 17 , 19 ], we decided to employ them without further purification.…”

“…Recently, we turned our attention to oxidized propargyl alcohols, namely ynones 2 , because of the interesting structure with two strongly electron-withdrawing moieties, resulting in a high electrophilicity. However, only a few methods have been reported thus far for their preparation [ 15 – 20 ], including one that appeared in 2020 [ 21 ]. However, they suffer from problems, such as the formation of the desired product 2 only as regioisomeric mixtures [ 15 , 17 ] or the applicability to only one substrate without any extension to other related compounds [ 16 , 18 – 20 ]…”

Cesium Fluoride Catalyzed Trifluoromethylation of Esters, Aldehydes, and Ketones with (Trifluoromethyl)trimethylsilane

“…In this study we found that CsF is a very good initiator for the trifluoromethylation of esters, aldehydes, and ketones. Within 1−4 h, esters 7a − g reacted with TMS−CF 3 to give the corresponding trifluoromethylated silyl ethers ( 8a − g ), which upon acid hydrolysis afforded the products noted in excellent isolated yields ( 9a − f ) (Scheme , Table ). ,− Known compounds were identified by comparing their spectral data with the literature. It should be mentioned that no double addition products were formed, indicating that, under these conditions, the esters are more reactive than the products formed.…”

The Usefulness of Phosphorus Compounds in Alkyne Synthesis

“…For example, the synthesis of fluorinated alkynes, containing perfluoroalkyl or perfluoroaryl groups, by the pyrolysis of the corresponding b-keto ylides was of considerable importance. Thus, a large variety of phosphonium salts containing electron-withdrawing groups R 1 [R 1 = CN, 38,[65][66][67][68] 69,70 CONR 2 , 71 COSMe, 36 CHO, 72 COR, 73,74 alkenyl, 75 aryl, [12][13][14][15][16][17][76][77][78] aryloxy, 79 2-thienyl 80 ] and perfluorinated groups R 2 were prepared and thermally decomposed to give the corresponding alkynes in moderate to excellent yield.…”

“…The diethyl dibromomethylphosphonate (76) was prepared from the diethyl chloromethylphosphonate (68). 272 The lithium carbenoid 69, generated by adding BuLi to 68 at -75 °C, was treated at the same temperature with tetrabromomethane in the presence of lithium bromide for 40 min to give the 1-bromo-1-chloro-1-lithiomethylphosphonate (73). At -70 °C, due to metal-assisted ionization, 73 behaves as an electrophile and as such it reacts with LiBr to give mainly the 1,1-dibromo-1-lithiomethylphosphonate (74).…”