174359-97-8Relevant academic research and scientific papers
Axially chiral cyclopentadienyl ligands: Stereoselective synthesis of 1-substituted-9-(1′-naphthyl)fluorenes and retention of axial chirality in the fluorenyl carbanions
Baker, Robert W.,Foulkes, Michael A.,Taylor, James A.
, p. 1047 - 1057 (2007/10/03)
1-(tert-Butyl- or 1-(p-tolyl-sulfinyl)naphthalene-2-carboxylate esters undergo coupling reactions with fluorenyllithiums substituted at the 1-position, providing 1-(1′-substituted-fluoren-9′-yl)naphthalene-2-carboxylate esters as single rotamers where the naphthalene ester substituent is syn to the fluorene 9-H. The stereoselectivity of the coupling reaction, with respect to asymmetric induction at the fluorene 9-C, varies from 21-95% (ee or de) dependant on the sulfoxide, ester and fluorene substituents, and the reaction temperature. The stereomutation of +ac(R)-1-methyl-9-(2′-methoxymethyl-1′-naphthyl)fluorene 33 into ent-33 was achieved through thermal atropisomerisation of 33 to the -sc(R)-rotamer 34, followed by lithiation of 34 and then reprotonation of the resultant fluorenyllithium 35, demonstrating the retention of axial chirality in the fluorenyl carbanion.
Asymmetric 9-(1'-Naphthyl)fluorenes: Enantioselective Synthesis, Determination of Absolute Configuration and Retention of Axial Chirality in the Fluorenyl Carbanions
Baker, Robert W.,Hambley, Trevor W.,Turner, Peter
, p. 2509 - 2510 (2007/10/03)
The rotamers of 1-methyl-9-fluorene 10 and 11 were synthesised enantioselectively via ligand coupling reactions of 1-(alkyl or arylsulfinyl)naphthalene-2-carboxylate esters with 1-methylfluorenyllithium and the absolute configurations established by a single crystal X-ray study of the (1R)-menthyl ester 4; deprotonation of 10 and 11 affords fluorenyl carbanions, ent-12 and 12, respectively, which retain axial chirality.
