title: A new efficient route to chiral 1,3-disubstituted ferrocenes: application to the syntheses of (R(p))- and (S(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol.
abstract: Starting from (2S,4S)-2-ferrocenyl-4-(methoxymethyl)-1,3-dioxane (4), use of the stereogenic ortho-directing menthyl para-tolyl sulfoxide group, which occupies the 2' position in the ferrocenyl ring and redirects subsequent lithiation to the 3' position, allowed the synthesis of optically pure (S(p))-1-formyl-3-iodoferrocene (8), that was characterized by single-crystal X-ray diffraction. Combination of this method with a protection-deprotection strategy, using trimethylsilyl as a temporary blocking group, yielded (R(p))-1-formyl-3-iodoferrocene (13). Separate Sonogashira coupling of each of the enantiomeric iodoformylferrocenes 8 and 13 with 17alpha-ethynyl-estradiol produced (R(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol (14) and (S(p))-17alpha-[(3'-formylferrocenyl)ethynyl]estradiol (15), respectively.
authors.affiliation: Laboratoire de Chimie et Biochimie des Complexes Moléculaires, UMR-CNRS 7576, Ecole Nationale Supérieure de Chimie de Paris, 11 rue P. et M. Curie, 75231 Paris cedex 05, (France).
authors.forename: Benoît
authors.initials: B
authors.lastname: Ferber
authors.forename: Siden
authors.initials: S
authors.lastname: Top
authors.forename: Richard
authors.initials: R
authors.lastname: Welter
authors.forename: Gérard
authors.initials: G
authors.lastname: Jaouen