15774-73-9Relevant articles and documents
Catalyst-Controlled Stereoselective Barton–Kellogg Olefination
Schmidt, Tanno A.,Sparr, Christof
supporting information, p. 23911 - 23916 (2021/10/08)
Overcrowded alkenes are expeditiously prepared by the versatile Barton–Kellogg olefination and have remarkable applications as functional molecules owing to their unique stereochemical features. The induced stereodynamics thereby enable the controlled motion of molecular switches and motors, while the high configurational stability prevents undesired isomeric scrambling. Bistricyclic aromatic enes are prototypical overcrowded alkenes with outstanding stereochemical properties, but their stereocontrolled preparation was thus far only feasible in stereospecific reactions and with chiral auxiliaries. Herein we report that direct catalyst control is achieved by a stereoselective Barton–Kellogg olefination with enantio- and diastereocontrol for various bistricyclic aromatic enes. Using Rh2(S-PTAD)4 as catalyst, several diazo compounds were selectively coupled with a thioketone to give one of the four anti-folded overcrowded alkene stereoisomers upon reduction. Complete stereodivergence was reached by catalyst control in combination with distinct thiirane reductions to provide all four stereoisomers with e.r. values of up to 99:1. We envision that this strategy will enable the synthesis of topologically unique overcrowded alkenes for functional materials, catalysis, energy- and electron transfer, and bioactive compounds.
Palladium-catalyzed intramolecular direct arylation of benzoic acids by Tandem decarboxylation/C-H activation
Wang, Congyang,Piel, Isabel,Glorius, Frank
supporting information; experimental part, p. 4194 - 4195 (2009/09/30)
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Reactions of carbene intermediates from the reaction of trialkyl phosphites with dialkyl benzoylphosphonates: Intramolecular cyclisations of 2-substituted dialkyl benzoylphosphonates
Griffiths, D. Vaughan,Griffiths, Penelope A.,Karim, Khalku,Whitehead, Belinda J.
, p. 555 - 561 (2007/10/03)
The reaction of dialkyl benzoylphosphonates 1 with trialkyl phosphites leads to the formation of carbene intermediates 3 via the anionic intermediates 2. The carbene intermediates 3 (R = 2-PhO, 2-PhOCH2, and 2-PhS) have been generated by heating the corresponding 2-substituted dialkyl benzoylphosphonates with trimethyl phosphite and their subsequent reactions investigated. Reactions proceed either by intermolecular trapping of the carbene intermediates by trimethyl phosphite to give novel ylidic phosphonates 4, or by intramolecular routes involving carbene insertion into the π-system of the phenyl ring in the substituent. Studies using methyl-substituted derivatives have shown that the formation of the thioxanthenylphosphonate 15 (X = S, R′ = R″ = Me) proceeds via a spiro diene intermediate 14 (X = S, R′ = R″ = Me).
