Cholesterol tagged with the BODIPY fluorophore via the central difluoroboron moiety of the dye (B-Chol) is a promising probe for studying intracellular cholesterol dynamics. We synthesized a new BODIPY-cholesterol probe (B-P-Chol) with the fluorophore attached via one of its pyrrole rings to carbon-24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion microscopy, performed for the first time, to our knowledge, with fluorescent sterols, revealed that the difference in lateral diffusion of the BODIPY-cholesterol probes was not caused by anomalous subdiffusion, because diffusion of both analogs in the PM was free but not hindered. Our combined measurements show that the position and orientation of the BODIPY moiety in cholesterol analogs have a severe influence on lateral diffusion specifically in the PM of living cells.

Colloidal gold particles with functionalized organic shells were applied as novel selectin binders. The ligand shell was terminated with different monocyclic carbohydrate mimetics as simplified analogs of the sLe x unit found in biological selectin ligands. The multivalent presentation of the sulfated selectin binding epitopes on the gold particles led to extremely high binding affinities towards L-and P-selectin and IC 50 values in the subnanomolar range. Depending on the ring size of the sulfated carbohydrate mimetic, its substitution pattern and its configuration, different selectivities for either L-selectin or P-selectin were obtained. These selectivities were not found for gold particles with simple acyclic sulfated alcohols, diols and triols in the ligand shell. In addition, the influence of the particle size and the thickness of the hydrophobic organic shell were systematically investigated.

A series of 3,3¢-disubstituted and 6,6¢-disubstituted BINOL derivatives was synthesized and examined in typical titanium(IV) promoted aldol reactions. The model reaction of S-ketene silyl acetal 13 and aldehydes 12a and 12b revealed that 6,6¢-dibromo-BINOL derivative (R)-6 is the ligand of choice for these transformations. Up to 97% yield with excellent enantioselectivity (ee > 97%) could be achieved. Scope and limitations were demonstrated using a series of aldehydes as substrates, which were generally transformed into their aldol adducts by the (R)-6/Ti(Oi-Pr) 4 catalyst with good efficacy and high enantioselectivity.

Starting from enantiopure 3,6-dihydro-2H-1,2-oxazines syn-1 we introduced an additional hydroxy group in a stereoselective fashion by a standard hydroboration/oxidation protocol. Under "regular" conditions substrate control was sufficient to achieve a very high degree of stereoselectivity. However, a diastereomeric product was isolated when a partially "degraded" borane reagent was used. We could synthesise this new diastereomer on purpose by addition of alcohols to the "fresh" hydroboration reagent. The level of stereoinduction increased with the steric bulk of the added alcohol: MeOH Ͻ nBuOH Ͻ iPrOH Ͻ tBuOH. After a twostep oxidation/reduction sequence, another 5-hydroxy-1,2-oxazine epimer was accessible. The obtained 5-hydroxy-1,2-oxazine diastereomers 2 were used as versatile intermediates

Enantioselective syntheses O 0031 Functionalized BINOL Derivatives as Ligands for Enantioselectively Catalyzed Aldol Additions: Highly Enantioselective Synthesis of Chiral β-HydroxyThioesters. -A number of BINOL-derivatives of type (I) and (II) is prepared and examined in an asymmetric model reaction, the addition of S-ketene silyl acetal (II) to aldehydes (IIII). Best results are obtained with derivative (Ia) and various aldol products are obtained in excellent enantioselectivity. -(ZIMMER*, R.; SCHEFZIG, L.; PERITZ, A.; DEKARIS, V.; REISSIG, H.-U.; Synthesis 2004, 9,