Search

Two examples of N-aryloxy-β-diketiminate dianions (11a,b) have been synthesized on a multigram scale, in four steps, from commercially available chemicals. The synthetic scheme relies on the sequen...

A domino 1,4-addition/alkyne carbozincation sequence basedon a radical zinc-atom transfer process is disclosed. Two efficientmulticomponent approaches to 3-alkylidenetetrahydrofurans from β-(propargyloxy)enoatesbearing pendant alkynes (including ynamides) have been established:one involving the direct addition of dialkylzincs, and the secondinvolving the dimethylzinc-mediated addition of alkyl iodides. Bothsequences utilize the stereoselective formation of intermediatealkylidenezincs well suited for in situ functionalizationwith electrophiles. 1 Introduction 2 1,4-Addition/Cyclization of Dialkylzincs on β-(Propargyl-oxy)enoates 2.1 β-(Propargyloxy)enoates with a Pendant TerminalAlkyne 2.2 β-(Propargyloxy)enoates with a Pendant Substituted Alkyne 2.3 β-(Propargyloxy)enoates with a Pendant Ynamide 3 1,4-Addition/Cyclization of Alkylzinc Halides on β-(Propargyloxy)enoates 4 Dialkylzinc-Mediated 1,4-Addition/Cyclization ofAlkyl Iodides on β-(Propargyloxy)enoates 5 Conclusion; Current and Future Work

When 4-nitro-AF4 is treated with nucleophiles such as alkoxides and cyanide, a novel ring opening, cyclophane destroying reaction is observed whereby, via an S N Ar mechanism, the nucleophile attacks the bridgehead aryl carbon vicinal to the nitro group with subsequent aryl-CF 2 bond cleavage.

The formation of alkylidenezinc carbenoids by 1,4-addition/carbozincation of dialkylzincs or alkyl iodides based on zinc atom radical transfer, in the presence of dimethylzinc with β-(propargyloxy)enoates having pendant iodo- and bromoalkynes, is disclosed. Formation of the carbenoid intermediate is fully stereoselective at −30 °C and arises from a formal anti-selective carbozincation reaction. Upon warming, the zinc carbenoid is stereochemically labile and isomerizes to its more stable form.

A new class of functionalized β-diketiminate ligands has been prepared from commercially available reagents. The novel N-aryloxy-β-diketiminate ligand proves to be an excellent ligand to support 4d, 4f and 5f metal ions.

When 4-nitro-AF4 is treated with nucleophiles such as alkoxides and cyanide, a novel ring opening, cyclophane destroying reaction is observed whereby, via an S N Ar mechanism, the nucleophile attacks the bridgehead aryl carbon vicinal to the nitro group with subsequent aryl-CF 2 bond cleavage.

Complete assignment of the (1)H and (19)F chemical shifts in 4-fluoro-AF4 (1) were based on the nOes seen in its (19)F-(1)H HOESY spectrum. This allowed for identification of features which can further be applied to the assignment of the regiochemistry of substituted perfluoroparacyclophanes (PCPs) and AF4s: (i) an aromatic fluorine couples with the two fluorines in the closest bridge that are syn to it, with constants of ca. 20 Hz; (ii) an aromatic fluorine couples with the bridge fluorine five bonds away that is anti to it in the same paraphenylene moiety, with a constant of ca. 3.5 Hz; (iii) the geminal coupling of the bridge fluorines is 246 Hz if they have an ortho fluorine and 238 Hz if they do not; (iv) a bridge fluorine couples with those aromatic protons in the same paraphenylene moiety that are four or five bonds away and anti. These features have been used to assign the regiochemistry of the pseudo-ortho, pseudo-meta and pseudo-para-difluoro AF4s 2-4. It has also been demonstrated that SCS for the bridge fluorines can be used as well for this assignment.

The first examples of inorganic nitrite complexes of the natural actinides are described, including the structures of the homoleptic thorium(IV) [PPh(4)](2)[Th(NO(2))(6)] and the uranyl(VI) [PPh(4)](2)[UO(2)(NO(2))(4)] complexes; the nitrite ligand can adopt two different coordination modes in the coordination sphere of the uranyl ion and is unstable towards reduction.