(+)--Chlorido-{2-[()-2-(methyl-sulfan-yl)ferro-cen-yl]-2,5,6,7-tetra-hydro-pyrrolo-[1,2-]imidazol-3-yl-idene}bis(tri-phenyl-phosphane-κ)palladium(II) hexa-fluorido-phosphate di-chloro-form disolvate.

The title solvated complex, [FePd(CH)(CHNS)Cl(CHP)]PF·2CHCl, bearing a chiral ferrocenyl pyrrolo-imidazolyl-idene -heterocyclic carbene (NHC) ligand, was synthesized by oxidative addition of a chloro-imidazolium salt to Pd(PPh). The Pd ion is coordinated in a slightly distorted square-planar coordination geometry, with the Cl atom to the coordinating C atom of the pyrrolo-imidazolyl-idene ligand. The complex features a pendant thio-ether group that is not involved in coordination to Pd.

Synthesis and first use of pyridine-2,6-diylbis(pyrazine-2-ylmethanone) in metal cluster chemistry: a {Mn(III)3Na2} complex with an ideal trigonal bipyramidal geometry.

The successful organic synthesis of a new dipyrazole/pyridine-dicarbonyl organic molecule, namely pyridine-2,6-diylbis(pyrazine-2-ylmethanone) [(pz)CO(py)CO(pz)], followed by its employment in Mn coordination chemistry has yielded the neutral cluster compound [Mn3Na2O(N3)3(L)3] (1), where L(2-) is the (pz)C(CH2COCH3)(O(-))(py)C(CH2COCH3)(O(-))(pz) dianion. The latter group was formed in situ, presumably by the nucleophilic attack of the carbanion (-)CH2COCH3 to the carbonyl carbon atoms of (pz)CO(py)CO(pz), in the presence of Mn(n+) ions under basic conditions and in solvent Me2CO. Complex 1 possesses an almost ideal trigonal bipyramidal topology, with the two Na(I) ions occupying the apical positions and the three Mn(III) ions residing in the equatorial trigonal plane.

Stereoselective synthesis of 5-substituted pyrrolo[1,2-c]imidazol-3-ones: access to annulated chiral imidazol(in)ium salts.

A two-step synthesis of N-heterocyclic carbene (NHC) precatalysts by diastereoselective or enantioselective lithiation of pyrrolo[1,2-c]imidazol-3-ones followed by POCl(3)-induced salt formation is described. The resulting 3-chloro-pyrroloimidazol(in)ium salts may be coordinated to palladium(II) upon NHC generation with t-BuLi at low temperature. The method may facilitate exploitation of these compounds as chiral organocatalysts or ligands in metal catalysis.

Aminoferrocene lithiation by boron trifluoride activation.

Lithiation of BF 3-complexed dimethylaminoferrocene occurs exclusively ortho to the dimethylamino group in the cyclopentadienyl ring providing structurally diverse products in 76-94% yield after electrophile quench. This method represents the first direct C2-lithiation of a monosubstituted aminoferrocene, offering rapid and complementary access to this class of compounds over procedures that utilize carbon- and sulfur-based directing groups and may serve as a prelude to an asymmetric process.

Directed ortho metalation-cross coupling strategies. N-cumyl arylsulfonamides. Facile deprotection and expedient route to 7- and 4,7-substituted saccharins.

By using the powerful N-cumylsulfonamide directed metalation group (DMG), a series of 2-substituted derivatives were prepared according to the directed ortho metalation (DoM) tactic (Table 1). Mild conditions for N-decumylation and other simple transformations of the products have been achieved (Scheme 2). The 3-silyloxy sultam 12 undergoes further DoM to give formyl, thiomethyl, iodo, and amide derivatives 13a-g of potential value for saccharin synthesis (Table 2).

An experimental and theoretical study of the asymmetric lithiation of 1,2,3,5,6,7-hexahydro-3a,4a-diazacyclopenta[def]phenanthren-4-one.

The inability of bis-N-Boc-protected octahydrophenanthroline to undergo asymmetric lithiation with (-)-sparteine is circumvented by use of a urea functionality as the directing group. Asymmetric lithiation followed by electrophile quench gives products substituted alpha to nitrogen in better yield (17-30%) but slightly lower enantiomeric ratio (er 84:16) than analogous lithiation of N-Boc-piperidine (er 87:13). Computational studies at the MP2/6-316(d)//B3LYP/6-316(d) level indicate that the prochiral equatorial S-hydrogen is removed preferentially over the pro-R hydrogen, with a difference in transition state activation energies of 1.

A benzimidazole-based N-heterocyclic carbene derived from 1,10-phenanthroline.

[reaction: see text] A catalytically active palladium-complexed tetracyclic N-heterocyclic carbene (NHC) was prepared in three steps from commercially available 1,10-phenanthroline by using a reduction-cyclization-deprotonation sequence. The new carbene framework is a prototype for the development of a series of chiral N-heterocyclic carbenes.

Synthesis of louisianin C.

The synthesis of louisianin C (3), a member of a small family of 3,4,5-trisubstituted pyridyl natural products, is achieved in six steps and 11% overall yield starting from commercially available 3,5-dibromopyridine. The key step is a fluoride-induced desilylation-cyclization to afford carbinol 12.

(-)-Sparteine-mediated metalation of ferrocenesulfonates. The first case of double asymmetric induction of ferrocene planar chirality.

[reaction: see text] A new process for induction of planar chirality via a matched chiral-directed metalation group (DMG)/(-)-sparteine interaction is demonstrated. Thus, s-BuLi metalation of (-)-menthylferrocenesulfonate (8b) with (-)-sparteine constitutes a matched pair resulting in amplification of the dr in the 2-formyl product 10a.