Oxidative cyclization of .delta.,.epsilon.- and .epsilon.,.zeta.-unsaturated enol silyl ethers and unsaturated siloxycyclopropanes

A concise enantioselective synthesis and cytotoxic evaluation of the anticancer rotenoid deguelin enabled by a tandem Knoevenagel/conjugate addition/decarboxylation sequence

“…22 The requisite TBS silyl enol ether 20 was first synthesized through treatment of enantioenriched chromanone 3 with triethylamine, TBSCl and NaI. 41 The resulting TBS ether ( 20 ) was then exposed to Cu(OTf) 2 /Cu 2 O in the presence of 2,6-di- t -butylpyridine (DTBP).…”

An Umpolung Strategy for the Synthesis of β-Aminoketones via Copper-Catalyzed Electrophilic Amination of Cyclopropanols

“…Similarly, cyclopropanol 1s gave desired product 4s in 76= yield and no cyclized product 8 was isolated indicating a non-radical cyclo-propanol ring-opening process (Figure 4, Eq.3). 19 These two notions are further supported by the insensitivity of the reaction to the addition of 1.0 equiv of TEMPO (Figure 4, Eq.4).…”

Efficient Synthesis of β-CF3/SCF3-Substituted Carbonyls via Copper-Catalyzed Electrophilic Ring-Opening Cross-Coupling of Cyclopropanols

“…When substrate 5w was used in the trifluoromethylthiolation reaction, 7w was produced in 54% yield and the terminal olefin is tolerated under the reaction conditions. In this case, no cyclized product 23 was observed, indicating that copper-promoted radical cyclopropanol ring-opening process to produce an β-alkyl radical was unlikely 15 and copper-promoted β-carbon elimination might be involved to generate a copper-homoenolate. When enone 18 was subjected to the trifluoromethylation or trifluoromethylthiolation reaction, no 6a or 7a were obtained respectively, which suggest that α,β-unsaturated ketone intermediate is not involved in the production of the desired product.…”