54812-97-4Relevant articles and documents
Synthesis of Highly Oxygenated Carbocycles by Stereoselective Coupling of Alkynes to 1,3- and 1,4-Dicarbonyl Systems
Kier, Matthew J.,Leon, Robert M.,O'Rourke, Natasha F.,Rheingold, Arnold L.,Micalizio, Glenn C.
, p. 12374 - 12377 (2017)
Densely substituted and highly oxygenated carbocycles are challenging targets for synthesis. In particular, those possessing numerous contiguous, fully substituted carbon atoms (i.e., tertiary alcohols and quaternary centers) are often not accessible in a direct fashion, necessitating the strategic decoupling of ring-formation from the establishment of functionality about the system. Here, we describe an approach to the construction of highly oxygenated mono-, di-, and polycyclic carbocycles from the reaction of disubstituted alkynes with β- or γ-dicarbonyl systems. These processes embrace a variant of metallacycle-mediated annulation chemistry where initial alkyne-carbonyl coupling is followed by a second, now intramolecular, stereoselective C-C bond-forming event. In addition to revealing the basic reactivity pattern in intermolecular settings, we demonstrate that this class of reactivity is quite powerful in a fully intramolecular context and, when terminated by a stereoselective oxidation process, can be used to generate polycyclic systems containing a fully substituted and highly oxygenated five-membered ring.
Titanocene catalysed 5-exo cyclisations of unsaturated epoxides- reagent control in radical chemistry
Gansaeuer,Pierobon,Bluhm
, p. 2500 - 2520 (2007/10/03)
A synthetic route to carbocyclic and heterocyclic [3.3.0], [4.3.0] and [5.3.0] systems containing pyrrolidine and tetrahydrofuran units and various other tetrahydrofuran derivatives is presented. The products are of relevance for natural product synthesis and for the synthesis of biologically active compounds. The titanocene catalysed reactions utilises readily available unsaturated epoxides as substrates. A model explaining the diastereoselectivity of cyclisation is presented that should allow for rational design of more selective catalysts.
