Organolanthanide reagents and the Mukaiyama reaction

Technical Report · Sun Jan 01 04:00:00 EST 1989

DOI:https://doi.org/10.2172/6476336· OSTI ID:6476336

Gong, L

The bis(pentamethylcyclopentadienyl) lutetium halide complex ((C/sub 5/Me/sub 5/)/sub 2/LuCl/center dot/THF) was synthesized and characterized. The crystal structure of this complex shows that the Lu is at the center of a distorted tetrahedron consisting of the centroids of two cyclopentadienyl rings, the oxygen atom of a tetrahydrofuran molecule and a chlorine atom. /sup 1/H NMR studies of toluene-d/sub 8/ solutions of (C/sub 5/Me/sub 5/LuCl(THF) + THF, (TMS/sub 2/CP)/sub 2/LuCl(THF) + THF, and (MeCp)/sub 2/LuCl(THF) + THF at various temperatures showed exchange processes between co- ordinated THF and free THF with average values of ..delta..G/sup ne/ of 13.0 /+-/ 0.3 kcal/mol, 11.1 /+-/ 0.1 kcal/mol and <11 kcal/mol at 0/degree/C, respectively. It has been found that under the influence of a catalytic amount (1--5 mol %) of (TMS/sub 2/Cp)/sub 2/YbCl dimer, silyl enol ethers (R/sub 1/R/sub 2/C = C(OR/sub 3/)OSiMe/sub 3/)) react with benzaldehyde smoothly in dichloromethane at room temperature, giving >99% of the aldol silyl ether (isolated yield: 90%) within 3 h. At /minus/78/degrees/C, the reaction gives kinetically controlled diastereoselectivity, which was not observed in the TiCl/sub 4/-mediated aldol reaction. The use of organoytterbium enolates shows promise result with respect to increased stereoselectivity, and indicates the importance of the bulky ligands on the metal center. In addition, Yb(III) species can retard retroaldol reaction owing to its mild Lewis acidity. 118 refs., 14 figs., 30 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6476336
• Report Number(s): LBL-26680; ON: DE89008166
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
ACTIVATION ENERGY
ALDEHYDES
ALKALI METAL COMPOUNDS
BENZALDEHYDE
BOND LENGTHS
CERIUM COMPOUNDS
CHEMICAL PREPARATION
CHEMICAL SHIFT
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
COMPLEXES
DIENES
DIFFRACTION
DIMENSIONS
ENERGY
FURANS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
LENGTH
LUTETIUM CHLORIDES
LUTETIUM COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PENTADIENES
POLYENES
RARE EARTH COMPLEXES
RARE EARTH COMPOUNDS
SAMARIUM COMPLEXES
SCATTERING
SODIUM COMPOUNDS
STEREOCHEMISTRY
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TETRAHYDROFURAN
X-RAY DIFFRACTION
YTTERBIUM CHLORIDES
YTTERBIUM COMPOUNDS