130225-27-3Relevant articles and documents
Two approaches in the synthesis of planar chiral azinylferrocenes
Utepova, Irina A.,Chupakhin, Oleg N.,Serebrennikova, Polina O.,Musikhina, Alexandra A.,Charushin, Valery N.
, p. 8659 - 8667 (2014)
Two synthetic routes to the chiral azinylferrocenes (CAFs) 5 and 15, key intermediates for the synthesis of new enantiomerically enriched P,N-ligands, have been compared. The first approach is based on the palladium-catalyzed cross-coupling reaction of halogenated azines with organozinc derivatives of ferrocenes (the Negishi reaction). The second approach exploits a new synthetic methodology, which provides a shorter pathway, through the direct C-H functionalization of aromatics by the C-C coupling of halogen-free (hetero)arenes with lithium ferrocenes bearing stereogenic C and S atoms. The palladium complexes of P,N-ligands have been used as catalysts for the Tsuji-Trost reaction, which proceeds with high enantioselectivity to give allylic substitution products in good yields.
Intramolecularly sulfur-stabilized silicon cations as Lewis acid catalysts
Rohde, Volker H. G.,Pommerening, Phillip,Klare, Hendrik F. T.,Oestreich, Martin
, p. 3618 - 3628 (2014/08/05)
The synthesis and spectroscopic characterization of previously unprecedented sulfur-stabilized silicon cations are reported. Several 1,3-dithiolan-2-yl- and 1,3-dithian-2-yl-substituted silanes were prepared and successfully transformed into the corresponding silicon cations by hydride abstraction. The silicon-sulfur interaction creates three consecutive stereocenters at three different elements. It is remarkable that the present stereocenter at the silicon atom determines the stereochemical outcome at the formerly prochiral sulfur and carbon atoms with excellent diastereoselectivity. All sulfur-stabilized silicon cations are shown to be potent catalysts in a challenging Diels-Alder reaction. Moreover, structurally related oxazoline-stabilized silicon cations were generated and characterized but found to be unreactive.
Synthesis and reactivity of achiral and of a novel planar chiral thioferrocenoylsilanes
Bonini, Bianca F.,Comes-Franchini, Mauro,Fochi, Mariafrancesca,Mazzanti, Germana,Ricci, Alfredo,Tomasulo, Massimiliano,Varchi, Greta
, p. 407 - 417 (2007/10/03)
The reactions of thioferrocenoylsilanes with organolithium reagents, dienes and reducing agents which afford α-silyl sulphides, dihydrothiopyranes and α-silyl ferrocenyl thiols, respectively, have been investigated. α-Silyl sulphides were further functionalised through carbodesilylation with aldehydes. We also report the synthesis of a new planar chiral thioferrocenoylsilane that gave good diastereomeric excess in the reaction with t-butyllithium, lithium lutidine and 2,3-dimethylbuta-1,3-diene. The 1,1′-bis-thioferrocenoylsilane, too unstable to be isolated, was trapped in situ with dienes.
