Reactions of Vinylidenecyclopropanes with Diphenyl Diselenide in the Presence of AIBN and Further Transformation To Produce New Naphthalene Derivatives

C-H Diselenation and Monoselenation of Electron-Deficient Alkenes via Radical Coupling at Room Temperature

A new, simple, and metal-free route for the diselenation of maleimides has been first developed employing (bis(trifluoroacetoxy)iodo)benzene (PIFA) at room temperature. The present method is compatible with different functional groups, and various diselenyl maleimides were obtained in moderate to excellent yields. Moreover, this protocol further highlights the unique practical application for the functionalization of biologically relevant molecules and amino acid derivatives. Preliminary mechanism studies suggest that radicals may be involved in this novel transformation. Additionally, this protocol is also applicable for the monoselenation of maleimides by switching the reaction conditions and selenation of other electron-deficient alkenes.

Synthesis of 1,2-diselenides via potassium persulfate-mediated diselenation of allenamides with diselenides

An efficient potassium persulfate-mediated radical addition of allenamides with diselenides was developed to create a workable route to 1,2-diselenide products. The reaction tolerates a wide spectrum of functional groups to deliver the products in good to excellent yields. Mechanistic investigations including a calculation study indicated that the radical cascade proceeds through a vinyl radical intermediate, which is formed via a selenium radical added to the terminal CC double bond of allenamides.

Hexafluoroisopropanol-Promoted Disulfidation and Diselenation of Alkyne, Alkene, and Allene

Hexafluoroisopropanol (HFIP)-promoted disulfidation and diselenation of C-C unsaturated bonds is reported. Reactions of unactivated alkyne, alkene, and allene, respectively, with disulfides or diselenides in HFIP led to desired products in good to excellent yields (up to 96%). In contrast, other solvents, such as isopropanol and dichloroethane, could not promote the same reaction. This method revealed an example of HFIP-promoted transformations under the mild conditions, which greatly highlighted the unique reactivity of this special solvent.

Stereoselective synthesis of (2S,3S,4R,5S)-3,4-dihydroxy-2,5-dihydroxymethyl pyrrolidine from L-sorbose

One of the most frequently synthesized iminosugar derivatives is DMDP. Starting from L-sorbose, a practical method for the synthesis of derivatives of this five-membered iminocyclitol has been developed, involving straightforward steps and a convenient selective reduction of a ketoxime intermediate.

An "anti-Baldwin" 3-exo-dig cyclization: preparation of vinylidene cyclopropanes from electron-poor alkenes

Stabilized carbanions undergo an uncommon 3-exodig cyclization onto propargyl halides through an SN2' substitution. Propargyl iodides as electrophiles are necessary to achieve good yields (36-95%) for most substrates, although the usefulness of chlorides and bromides is documented. A variety of monocyclic and bicyclic vinylidene cyclopropanes can be prepared. These products are not available by standard carbene methodology.

Lewis Acid Catalyzed Rearrangement of Vinylcyclopropenes for the Construction of Naphthalene and Indene Skeletons

[reaction: see text] The choice of Lewis acid catalyst can result in dramatic differences in the chemoselectivity of the rearrangement reactions of vinylcyclopropenes. When BF3.OEt2 was used as the catalyst, naphthalenes were formed. However, when Cu(OTf)2 was used as the catalyst, indenes were obtained.