Chemistry Of Allenes Research Articles

Stereoselective Synthesis of Homopropargylic Allylic Ethers

In view of the recent upsurge in the chemistry of alkynes and allenes, practical methods to prepare them in enantiopure form are valuable. A wide variety of densely functionalized homopropargylic ethers were prepared in high diastereoselectivity by a one-pot, three component reaction. The authors used chiral allenylsilanes 2 as nucleophiles to add to aldehydes with complete transfer of chirality. Both enantiomers of the propargylic alcohol were obtained via an enzymatic kinetic resolution on the racemate of 1 on >35 g scale. The key chiral allenylsilane 2 was generated by a stereoselective Johnson-Claisen rearrangement.

Synthesis of a stable indium complex derived from γ-silyl-α,α-difluorobromopropyne: evaluation of experimental parameters

Fluoroallenes are potentially useful cyclization precursors because of the synergistic combination of fluorine’s unique stereolectronic features and the rich chemistry of allenes. We have optimized the experimental conditions needed for the formation of a difluoropropargylindium complex 2. Sonication, lower reaction temperatures (5 °C), and dilute concentration of the starting material (0.15 M) are required to maximize production of this complex. Although the structure of this complex remains unknown, we have found that the nature of the alkyl substituents on the silyl group does not influence the formation of 2 but it does affects the allenyl 5 to propargyl 4 ratio.

Comprehensive Model for the Electronic Structures of 1,2,4-Cyclohexatriene and Related Compounds

To gain a better understanding of the chemistry of cyclic allenes, in the present work six-membered monocyclic systems containing second- (B−O) and third-row elements (Al−S) of the periodic table of elements are studied in detail, regarding the energetic order of the electronic states and the planarization energies, which together determine their chemical behavior. The data obtained by high-level ab initio methods show that the properties of the compounds strongly depend on the heteroatoms and can be related to trends in the periodic table of elements. These trends in the series B to O and Al to S are rationalized by the degree of the interaction between the various fragments and the interplay between this interaction and the strain in the allene moiety. In addition, by applying the model to charged species, we reveal an unexpected link between the cyclic allenes and the phenyl anion. Furthermore, our computations answer open questions about the chemical properties of 1-aza-2,3-cyclohexadienes. Finally, w...

Book Review: The Chemistry of the Allenes. Edited by S. R. Landor

Book Review: The Chemistry of the Allenes. Edited by S. R. Landor