A catalytic asymmetric bromocyclization of trisubstituted olefinic amides that uses a C(2)-symmetric mannitol-derived cyclic selenium catalyst and a stoichiometric amount of N-bromophthalimide is reported. The resulting enantioenriched pyrrolidine products, which contain two stereogenic centers, can undergo rearrangement to yield 2,3-disubstituted piperidines with excellent diastereoselectivity and
Stereocontrolled one-pot synthesis of cyclopentane derivatives possessing quaternary carbon using allyl phenylsulfone and epoxyiodide was presented. Furthermore, application of this protocol to the synthesis of cycloalkane derivatives with different ring sizes was successful.
The PtCl2-catalyzed hydrosilylation of terminal alkynes with triethylsilane and subsequent alkenylation of aldehydes with the resultant (E)-alkenylsilanes in a one-pot manner are described. By adding p-benzoquinone and Lil, the latter alkenylation step proceeds smoothly to give allyl silyl ethers in moderate to high yields. This one-pot alkenylation is tolerant to a reasonable range of functional groups. PtCl2 plays a dual role as hydrosilylation and alkenylation catalysts.