5981-17-9Relevant articles and documents
An Unexpected “Step-Conjugated” Biphosphole via Unique P–P Bond Formation
Wang, Zisu,Asok, Nayanthara,Gaffen, Joshua,Gottlieb, Yael,Bi, Wenhua,Gendy, Chris,Dobrovetsky, Roman,Baumgartner, Thomas
supporting information, p. 2628 - 2643 (2018/11/30)
The synthesis of a π-conjugated organophosphorus species with bridging P–P unit is reported. Because of the pyramidal geometry of the phosphorus centers, the molecular scaffold provides intriguing electronic communication throughout the three-dimensional structure via π-σ-π conjugation in stepwise fashion. The dimeric species was serendipitously found to be accessible via a reaction of the corresponding P-amino-phosphole precursor through mediation with the hard Lewis acid BF3. We provide detailed mechanistic studies toward a suitable reaction mechanism that was also verified via computational means. Moreover, we elaborate the utility of the biphosphole via phosphorus functionalization that lends further proof for the step conjugation provided by the unique phosphorus-based molecular architecture. Fundamental chemistry lays the foundation for future innovation with considerable impact on next-generation technologies. Main-group chemistry in particular provides a unique angle with regard to structure and bonding, which makes it an intriguing state-of-the-art avenue for the development of readily accessible advanced materials with significantly value-added functionality, that is, optical and electronic properties. The need for innovative molecular architectures is particularly evident in the rapidly accelerating development of conjugated organic building blocks because their high utility for a variety of sustainable energy applications is now well established. Herein, we report a unique type of phosphorus-based “step-conjugated” building block via an unexpected reaction that we have elucidated mechanistically in our studies. Reaction of a P-amino-dithienophosphole with the hard Lewis acid, BF3, leads to a dimeric species via a P–P bond-forming reaction, as supported through systematic mechanistic studies. Because of the inherent pyramidal geometry of the phosphorus centers, the dimer shows extended step-like conjugation through the scaffold via π-σ-π conjugation, which makes it an intriguing new building block for organic hybrid materials.
Acetylenes as Potential Antarafacial Components in Concerted Reactions. Formation of Pyrroles from Thermolyses of Propargylamines, of a Dihydrofuran from a Propargylic Ether, and of an Ethylidenepyrrolidine from a β-Amino Acetylene
Viola, Alfred,Collins, John J.,Filipp, Nicholas,Locke, John S.
, p. 5067 - 5075 (2007/10/02)
A thermal cyclization of acetylenic compounds provides evidence for the ability of acetylenic links to act as antarafacial components in processes.The cyclization competes with the normally favored acetylenic retro-ene reaction.Propargylic amines, without substituents whose presence would hinder a tight cyclic transition state, yield intermediate pyrrolines whose subsequent hydrogen elimination affords pyrroles in small amounts.The same process in 2-ethynyltetrahydropyran affords 8-oxabicyclooctane in 35percent yield.A related thermal reaction of N-methyl-3-hexyn-1-amine provides a quantitative transformation to N-methyl-2-ethylidenepyrrolidine in a nominal s + 2a + 2s + 2s> Moebius process, wherein the acetylenic unit is the antarafacial component.Evidence for concertedness in these reactions is discussed.
