Enol Silyl Ethers and their Use for the Synthesis of α-Halo-α,β-unsaturated Carbonyl Compounds

Diastereoselective Total Synthesis of (±)‐Schindilactone A

“…Cyclopropanation of 9 with dibromocarbene [14] provided 10, which was subsequently treated with AgClO 4 [15] in acetone to give vinyl bromide 11 in 82 % yield after two steps. After palladium-catalyzed coupling of 11 with (1-tert-butoxyvinyloxy)(tert-butyl)dimethylsilane, [16] ketoester 12 was obtained in 85 % yield.…”

Diastereocontrol in the Synthesis of Models of Rings C and D of Phorbol: Directing Effect of an Ether Substituent on Lithium Carbenoid Mediated Cyclopropanation

“…Initially, the construction of the dimethylcyclopropane moiety was addressed by reaction of compound 15 with dibromocarbene13 and further transformation of the resulting dibromocompound with a homocuprate,14 to yield the dimethylated compounds 18 and 19 . Thus, when one equivalent of bromoform was added dropwise for one hour to a stirred slurry of compound 15 and potassium tert ‐butoxide in anhydrous pentane at −10 °C, dibromo compounds 16 and 17 were obtained (Scheme ).…”

Diastereoselective Total Synthesis of (±)‐Schindilactone A, Part 3: The Final Phase and Completion

“…After a systematic investigation, we found that the desired product (30) could be obtained in 90 % yield by the treatment of compound 29 with CHBr 3 in the presence of KOtBu in petroleum ether. [16] The dibromopropane that was generated was treated without purification with AgClO 4 [17] in acetone to give vinyl bromide 17 in 82 % yield over 2 steps. The structure of vinyl bromide 17 was established by X-ray crystallography (Scheme 4).…”

“…After a number of studies, we noted that the desired reaction could occur when CuF 2 was used as an additive and the reaction proceeded through the Pd-catalyzed cross-coupling of copper enolate [19] and vinyl bromide 17. Thus, the exposure of compound 17 3 } 2 ] (5 mol %) in the presence of CuF 2 (2.0 equiv) in THF at 75 8C gave the desired product (16) in 85 % yield (Scheme 5). The structure of ketoester 16 was confirmed by X-ray crystallography (Scheme 5).…”