Iridium complexes with chiral N,P ligands have emerged as a new class of highly efficient catalysts for asymmetric hydrogenation with an application range that is largely complementary to rhodium and ruthenium diphosphane complexes. [1][2][3] They have been used successfully for the hydrogenation of a wide range of functionalized and unfunctionalized di-and trisubstituted olefins. Unlike Rh and Ru diphosphane complexes, they do not require the presence of a coordinating group near the C=C bond, so even purely alkylsubstituted olefins can be hydrogenated with high enantioselectivity.[3] However, to date no practical catalysts are known for the asymmetric hydrogenation of unfunctionalized tetrasubstituted olefins. Although Buchwald and co-workers have obtained high enantioselectivities in the hydrogenation of tetrasubstituted aryl alkenes using a chiral zirconocene complex, [4] high catalyst loadings, long reaction times, and high sensitivity of the catalyst have prevented widespread use of this method. Ir catalysts based on chiral phosphanyl oxazoline (phox) ligands 1, [5] on the other hand, showed high activity in the hydrogenation of tetrasubstituted aryl alkenes such as 5, but enantiomeric excesses were at best moderate (Table 1). [1a, 6] We have recently found that Ir complexes based on the structurally simple and readily accessible phosphanyl oxazolines 4 are much better suited for such reactions.[7] A subsequent study with a wide range of ligands 4 and phosphinite oxazoline ligands of types 2 and 3 revealed that 5 and other tetrasubstituted olefins can be hydrogenated with high enantioselectivity at remarkably low catalyst loadings. Herein, we report the results of this study, which has led to highly efficient and practical Ir catalysts for the asymmetric hydrogenation of tetrasubstituted unfunctionalized olefins.Although the phosphanylmethyloxazoline 4 k was reported by Sprinz and Helmchen [8] many years ago, ligands of this type have not, to date, received much attention. [9] Using a modified synthetic route starting from two sets of secondary phosphanes and chloromethyloxazoline com-

The heterobimetallic peralkylated complexes [Ln(AlR4)2]n (Ln = Sm, Yb; R = Me, Et) were synthesized by a silylamide elimination route from Ln[N(SiMe3)2]2(THF)2 and an excess of AlR3. The solid-state structure of [Sm(AlEt4)2]n is isomorphous to that of the ytterbium derivative. Polymeric [Yb(AlMe4)2]n was examined by 1H and 13C MAS NMR spectroscopy revealing the presence of distinct bridging methyl groups. The reaction of [Yb(AlMe4)2]n and 1,10-phenanthroline (Phen) afforded the monomeric donor adduct Yb(AlMe4)2(Phen), while the protonolysis reaction with 2 equiv. C5Me5H (HCp*) yielded a separated ion pair of composition [Cp*Yb(THF)(4)][AlMe(4)]. Single-crystal X-ray diffraction data are provided for both ytterbium(II) complexes. Solid-state magnetic measurements (SQUID) were performed on [Sm(AlMe4)2]n, [Sm(AlEt4)2]n, SmI2(THF)2 and Sm[N(SiMe3)2]2(THF)2 showing high effective magnetic moments 3.67micro(B) < micro(eff) < 4.43micro(B).

(SmAl2Me8)x and (SmAl2Et8)x are obtained via a silylamide elimination reaction from Sm[N(SiMe3)2]2(THF)2 and excess AlR3 (R = Me, Et); (LnAl2Et8)x (Ln = Sm, Yb) react with THF, pyridine, and 1,10-phenanthroline to form the first donor adducts of homoleptic peralkylated Ln-Al heterobimetallic complexes.

The first synthesis of the natural product (+)-mutisianthol was accomplished in 11 steps and in 21% overall yield from 2-methylanisole. The synthesis of its enantiomer was also performed in a similar overall yield. The absolute configuration of the sesquiterpene (+)-mutisianthol was assigned as (1S,3R). Key steps in the route are the asymmetric hydrogenation of a nonfunctionalized olefin using chiral iridium catalysts and the ring contraction of 1,2-dihydronaphthalenes using thallium(III) or iodine(III). The target molecules show moderate activity against the human tumor cell lines SF-295, HCT-8, and MDA-MB-435.