Cycloadditions of 1-iminylphosphirane complexes with allenes

Metal-catalyzed [2+2+1] cycloadditions of 1,3-dienes, allenes, and CO.

Article: Step economy is a preeminent goal of synthesis. [1] It influences the length, efficiency, cost, time, separation, and environmental impact of a synthesis. Step economy is favored by the use of single, serial, or multicomponent reactions that proceed in one operation with a great increase in target revelant complexity. The design or discovery of such reactions is thus critical to extend...

Reactivity and Chemoselectivity of Allenes in Rh(I)-Catalyzed Intermolecular (5 + 2) Cycloadditions with Vinylcyclopropanes: Allene-Mediated Rhodacycle Formation Can Poison Rh(I)-Catalyzed Cycloadditions

Allenes are important 2π building blocks in organic synthesis and engage as 2-carbon components in many metal-catalyzed reactions. Wender and co-workers discovered that methyl substituents on the terminal allene double bond counterintuitively change the reactivities of allenes in [Rh(CO)2Cl]2-catalyzed intermolecular (5 + 2) cycloadditions with vinylcyclopropanes (VCPs). More sterically encumbe...

Metal Complexes versus Organocatalysts in Asymmetric 1,3-Dipolar Cycloadditions

The Molecular Structure of Allenes and Ketenes, XII [1] Four-Bond Proton-Proton Spin-Spin Couplings in Allenes

Allenes, Proton-Proton Coupling Constants, Substituent Effects Four-bond proton-proton coupling constants in allenes are reported. The substituent effects on the coupling constants are discussed on the basis of the dual-substituent parameter approach. Furthermore, the coupling constants are related to quantumchemical indices (electron densities, overlap populations) obtained from semiempirical ...

Propargyltrimethylsilanes as Allene Equivalents in Transition Metal-Catalyzed [5 + 2] Cycloadditions

Conventional allenes have not been effective π-reactive 2-carbon components in many intermolecular cycloadditions including metal-catalyzed [5 + 2] cycloadditions. We report herein that rhodium-catalyzed [5 + 2] cycloadditions of propargyltrimethylsilanes and vinylcyclopropanes provide, after in situ protodesilylation, a highly efficient route to formal allene cycloadducts. Propargyltrimethylsi...