The stereochemistry of an organic compound can have a profound influence on many of its most important properties. For example, the enantiomeric forms of a drug molecule can have completely different biological effects, and polymers that differ only in the stereochemistry of their backbones can have quite dissimilar macroscopic physical characteristics. Control over the stereochemical outcome o...

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol-ecule, C(10)H(16)O(6), in which the 1,5-lactone ring exists in a boat conformation. The use of d-galactose in the synthesis determined the absolute stereochemistry. The crystal exists as O-H⋯O hydrogen-bonded layers in the ab plane, with each mol-ecule acting as a donor and acceptor for tw...

A new, short and highly diastereoselective synthetic route aiming at the C(33)–C(37) fragment of Amphotericin B has been developed. Studies with a model aldehyde (benzaldehyde) have given very promising results: the desired stereochemistry of all four stereocenters of the target molecule has been achieved with high diastereoselection. The stereochemistry of three key intermediates and the targe...

The relative stereochemistry of tris-heteroleptic ruthenium complexes [Ru(pp)(pp')(pp'')](PF(6))(2), where pp = 1,10-phenanthroline-4-carboxamide, pp' = 5,6-dimethyl-1,10-phenanthroline, and pp'' = 7,8-dimethyl dipyrido[3,2-a:2',3'-c]phenazine, was studied using NMR spectroscopy. The (1)H and (13)C spectra were assigned by using double-quantum-filtered correlation spectroscopy (DQF-COSY), heter...

Studies for this thesis involve efforts toward the enantioselective total synthesis of taxusin (5). Key features of the synthetic sequence include a diastereoselective, intramolecular enone-olefin [2+2] photocyclization of photosubstrate 94 which introduces the correct stereochemistry of the C(8) methyl group. This reaction represents an unprecedented total reversal of stereochemistry from the ...

Several pyridoxal-phosphate-dependent enzymes can convert the bound cofactor to pyridoxamine phosphate. This conversion may be an obligatory part of the normal catalytic sequence, as with transaminases, or may be an abnormal path, inactivating the enzyme. This conversion requires protonation of the C(4)' carbon of the cofactor, which has now been shown to proceed stereospecifically and with the...

In this study, the reinforcement of ultrahigh-molecular-weight polyethylene (UHMWPE) with biotite was investigated. The biotite filler was mechanically activated with different dry surfactants to improve its compatibility with UHMWPE and decrease agglomeration among biotite particles. Alkyldimethylbenzylammonium chloride (ADBAC) and cetyltrimethylammonium bromide (CTAB) were selected as cationi...

Lipid stereochemistry was shown to drive cell internalization of liposomes through either clathrin or caveolae. Molecular dynamic simulations highlighted molecular interactions that affect physicochemical and biological features liposomes.

The sequential 1,4-elimination reaction of (E)-4-alkoxy-2-butenyl benzoates and [1,2]-Wittig rearrangement gave (2Z,4E)-2,4-pentadien-1-ols stereoselectively. Z-Selective formation of intermediary vinyl ethers, whose stereochemistry was well elucidated by the "syn-effect", was achieved by treatment of the 2-butenyl benzoates with KOH in the presence of Pd catalyst. The subsequent [1,2]-Wittg re...

A series of pentacyclic heterocyclic systems (15 examples, 69-89%) have been synthesized using intramolecular Povarov reactions involving 3-aminocoumarins and O-cinnamylsalicylaldehydes. The Povarov adducts are formed with high selectivity for the trans,trans relative stereochemistry in the newly-formed [6,6] fused ring system. One example of a Povarov adduct featuring a new [6,5] fused ring sy...