Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene

• Conrad Fischer,
• Wilhelm Seichter and
• Edwin Weber

Beilstein J. Org. Chem. 2011, 7, 1602–1608, doi:10.3762/bjoc.7.188

• -bromosuccinimide used, surprisingly only monosubstitution of the chalice is observed by application of the lithiation technique, independent of the amount of n-BuLi. However, twofold substitution on opposite methylene bridges can be achieved by successive application of the latter technique [6]. This may suggest

• potentially accessible for guest inclusion, which is also reflected by a comparatively low packing index (62.9) of the crystal [15]. Conclusion It was shown that the bridge monosubstitution of a basic calix[4]arene via lithiation requires a high conformational flexibility of the calixarene, which is the case

Gold(I)-catalyzed formation of furans by a Claisen-type rearrangement of ynenyl allyl ethers

• Florin M. Istrate and
• Fabien Gagosz

Beilstein J. Org. Chem. 2011, 7, 878–885, doi:10.3762/bjoc.7.100

• corresponding furans 7f, 7g, 7o, 7q and 7s in moderate to quantitative yields (entries 6, 7, 15, 17 and 19). It is also worth noting that an increase in the substitution at the terminus of the allylic moieties of the substrates (monosubstitution in the case of 6b, disubstitution for 6c–s) did not notably