A wide‐ranging study of Suzuki reactions which use nitrogen‐containing heterocycles is described (see scheme; dba=dibenzylideneacetone, Cy=cyclohexyl). This method is highly versatile (a single procedure was used for all substrates, including boronate esters and trifluoroborates), compatible with a variety of unprotected functionalities (e.g., NH2‐ and OH‐substituted substrates), and efficient even with unactivated aryl chlorides.

Eine umfassende Studie zu Suzuki‐Reaktionen mit Stickstoffheterocyclen wird vorgestellt (siehe Schema; dba=Dibenzylidenaceton, Cy=Cyclohexyl). Die Methode ist vielseitig (ein einziges Verfahren für alle Substrate einschließlich Boronatester und Trifluorborate), auf Substrate mit ungeschützten funktionellen Gruppen (NH2 und OH) anwendbar und auch für nichtaktivierte Arylchloride geeignet.

[reaction: see text] beta-Ketoesters can be effectively monofluorinated with F-TEDA using CpTiCl(3) as a catalyst. With the use of this catalyst, the extent of the competing difluorination does not reach 10%. [TiCl(2)(TADDOLato)] complexes catalyze the one-pot enantioselective heterodihalogenation of beta-ketoesters with F-TEDA and NCS to afford alpha-chloro-alpha-fluoro-beta-ketoesters in moderate to good yields. The sequence of addition of the halogenating agents determines the sense of chiral induction.

The substrate range of the [TiCl2(TADDOLate)] (TADDOL=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol)‐catalyzed asymmetric α‐fluorination of activated β‐carbonyl compounds has been investigated. Optimal conditions for catalysis are characterized by using 5 mol‐% of TiCl2(naphthalen‐1‐yl)‐TADDOLate) as catalyst in a saturated (0.14 mol/l) MeCN solution of F‐TEDA (1‐(chloromethyl)‐4‐fluoro‐1,4‐diazoniabicyclo[2.2.2]octane bis‐[tetrafluoroborate]) at room temperature. A series of α‐methylated β‐keto esters (3‐oxobutanoates, 3‐oxopentanoates) with bulky benzyl ester groups (60–90% ee) or phenyl ester (67–88% ee) have been fluorinated readily, whereas α‐acyl lactones were also readily fluorinated, but gave lower inductions (13–46% ee). Double stereochemical differentiation in β‐keto esters with chiral ester groups raised the stereoselectivity to a diastereomeric ratio (dr) of up to 96.5 : 3.5. For the first time, β‐keto S‐thioesters were asymmetrically fluorinated (62–91.5% ee) and chlorinated (83% ee). Lower inductions were observed in fluorinations of 1,3‐diketones (up to 40% ee) and β‐keto amides (up to 59% ee). General strategies for preparing activated β‐carbonyl compounds as important model substrates for asymmetric catalytic α‐functionalizations are presented (>60 examples).

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Oxocarboxylic acids and esters Oxocarboxylic acids and esters Q 0460Titanium-Catalyzed Stereoselective Geminal Heterodihalogenation of β-Ketoesters. -Monofluorination of β-ketoesters (I) and (IV) with Selectfluor proceeds smoothly in the presence of titanium catalysts to furnish the α-fluoroβ-ketoesters (II) and (V), resp., in moderate to good yields. The selectivity of mono-to difluorination reaches 10-30:1. The method can be extended to achieve an enantioselective heterodihalogenation. Thus, monofluorination in the presence of a chiral TiCl 2 ((R,R)-TADDOL) complex, followed by chlorination with NCS under analogous conditions furnishes the α-chloro-α-fluoro-β-ketoesters (III) and (VI) in moderate enantioselectivities. Changing the order of halogenation steps provides access to the corresponding stereoisomer. The introduction of a chiral auxiliary at the ester group does not significantly improve the selectivities. -(FRANTZ, R.; HINTERMANN, L.; PERSEGHINI, M.; BROGGINI, D.; TOGNI*, A.; Org. Lett. 5 (2003) 10, 1709-1712; Dep. Chem., Swiss Fed. Inst. Technol., ETH-Hoenggerberg, CH-8093 Zuerich, Switz.; Eng.) -Mischke 38-063 2003 Oxocarboxylic acids and esters

The chiral ferrocenyltriphosphane Pigiphos [bis{(S)‐1‐[(R)‐2‐(diphenylphosphanyl)ferrocenyl]ethyl}cyclohexylphosphane] forms four‐coordinate complexes with IrI and RhI. The tridentate ligand assumes different conformations in the derivatives [Rh(CO)(Pigiphos)]OTf (4) and [IrCl(Pigiphos)] (1b), the latter also showing a drastic deviation from the square‐planar geometry. Reactivity studies have focussed on the more reactive 1b. The HCl and O2 adducts have been characterized in solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

New hexamethylated ferrocene derivatives containing thioether moieties (1,1′‐bis[(tert‐butyl)thio]‐2,2′,3,3′,4,4′‐hexamethylferrocene (3a,b)) or fused S‐heteropolycyclic substituents (rac‐1‐[(1,3‐benzodithiol‐ 2‐yliden)methyl]‐2,2′,3,3′,4,4′‐hexamethylferrocene (5) and rac‐1‐[1,2‐bis(1,3‐benzodithiol‐2‐yliden)ethyl]‐2,2′,3,3′,4,4′‐hexamethylferrocene (14)), as well as a series of ferrocene‐substituted vinylogous tetrathiafulvalenes (1,1′‐bis[1,2‐bis(1,3‐benzodithiol‐2‐yliden)ethyl]ferrocene (6a), 1,1′‐bis[1‐(1,3‐benzodithiol‐2‐yliden)‐2‐(5,6‐dihydro‐1,3‐dithiolo[4,5‐b] [1,4]dithiin‐2‐yliden)ethyl]ferrocene (6b), [1,2‐bis(1,3‐benzodithiol‐2‐yliden)ethyl]ferrocene (21a), [1‐(1,3‐benzodithiol‐2‐yliden)‐2‐(5,6‐dihydro‐1,3‐dithiolo[4,5‐b] [1,4]dithiin‐2‐yliden)ethyl]ferrocene (21b), [1,2‐bis(5,6‐dihydro‐1,3‐dithiolo[4,5‐b] [1,4]dithiin‐2‐yliden)ethyl]ferrocene (21c), [1‐(5,6‐dihydro‐1,3‐dithiolo[4,5‐b] [1,4]dithiin‐2‐yliden)‐2‐(1,3‐benzodithiol‐2‐yliden)ethyl]ferrocene (21d)) were prepared and fully characterized. Their redox properties show that some of them are easily oxidized and undergo transformation to paramagnetic salts containing bis(maleonitriledithiolato)‐metallate(III) anions [M(mnt)2]− (M=Ni, Pt; bis[2,3‐dimercapto‐κS)but‐2‐enedinitrilato(2−)]nickelate (1−) or ‐platinate (1−). The derivatives [3a] [Ni(mnt)2] (26), [3a] [Pt(mnt)2] (27), [Fe{(η5‐C5Me4S)2S}] [Ni(Mnt)2] (28), [Fe{(η5‐C5Me4S)2S}] [Pt(mnt)2] (29), [5] [Ni(mnt)2]⋅ClCH2CH2Cl (30), [6a] [Ni(mnt)2] (31), [6a] [Ni(mnt)2]⋅ClCH2CH2Cl (31a), [6a] [Pt(mnt)2] [32), and [6b] [Ni(mnt)2] (33) were prepared and fully characterized, including by SQUID (superconducting quantum interference device) susceptibility measurements. X‐Ray crystal‐structural studies of the neutral ferrocene derivatives 6a,b, 21c,d, and 1,1′‐bis[1‐(1,3‐benzodithiol‐2‐yliden)‐2‐oxoethyl]ferrocene (23), as well as of the charge‐transfer salts 26 – 28, 30, and 31a, are reported. The salts 28 and 30 display both a D+A−A−D+ structural motif, however, with a different relative arrangement of the [{Ni(mnt)2}2]2− dimers, thus giving rise to different but strong antiferromagnetic couplings. Salt 26 exhibits isolated ferromagnetically coupled [{Ni(mnt)2}2]2− dimers. Salt 27 displays a D+A−D+A− structural motif in all three space dimensions, and a week ferromagnetic ordering at low temperature. Salt 31a, on the contrary, shows segregated stacks of cations and anions. The cations are connected with each other in two dimensions, and the anions are separated by a 1,2‐dichloroethane molecule.