BF3–OEt2-mediated rearrangement of 4-substituted-5,5-diphenylazepan-4-ols

BF3‐OEt2‐Mediated Rearrangement of (4‐Phenylpiperidin‐4‐Yl)‐Arylmethanols

“…First, two compounds 2a (R=Ms) and 2b (R=Ts) were synthesized via N-tosylation of compound 1 and reduction of the corresponding ester with lithium aluminum hydride in 79% and 82% yields, respectively. Further, alcohols 2a and 2b were converted into compounds 3a 1~3 a 3 and 3b 1~3 b 5 by PCC-mediated oxidation, Grignard addition (R 1 =Ph, 2-MePh, 3-MeOPh, 4-MeOPh, 4-FPh, and 2,6-Me 2 Ph), and followed by subsequent boron trifluoride etherate-mediated rearrangement in 75~88% yields. These experimental results are summarized in Table 1.…”

“…The possible mechanism was also shown in Scheme III. Compounds 3a 1~3 a 3 and 3b 1~3 b 5 were obtained as the single isomer via phenyl group 1,2-shift rearrangement and followed by proton abstract. The characteristic structure of compound 3b 5 was determined by single-crystal X-ray analysis as shown in Fig.…”

“…It is worth noting that products 3a 13 a 3 and 3b 1~3 b 5 are analogs with biological activities skeletons and could be applied in the preparation of structural framework A. Further novel application of this methodology with rearrangement formation of new carbon-carbon bonds is now underway.…”

“…[1][2][3][4][5] As shown in Scheme I, the relative position of nitrogen atom and oxygen atom is an important factor in the boron trifluoride etherate-mediated process. Boron trifluoride etherate has been reviewed for reactions involving carbon-carbon or carbon-heteroatom bond formations.…”

BF3.SiO2: An efficient heterogeneous alternative for regio-chemo and stereoselective claisen-schmidt condensation

“…In many synthetic reports, BF 3 .Et 2 O has been used. The silica supported form of BF 3 is a bench-top reagent which is easy to handle providing better accessibility of the reactants to the active sites [1].…”