Highly enantioselective reaction of lithiated N-Boc-thiazolidine: a new chiral formyl anion equivalent

Reaction of lithiated N-Boc-thiazolidine with various aldehydes in the presence of (-)-sparteine afforded the products with up to 93% ee. The reaction was confirmed to proceed through a dynamic thermodynamic resolution pathway. Each diastereomeric alcohol could be converted to the corresponding optically active 1,2-ethanediols.     

Triterpenoid total synthesis. Synthesis and absolute configuration of mispyric acid

The first synthesis of mispyric acid (1), an inhibitor of DNA polymerase beta with a novel triterpene skeleton, was achieved by starting from isoprene (2), geraniol (6) and 1,5-dimethoxy-1,4-cyclohexadiene (14). The absolute configuration of the naturally occurring 1 was determined as 2S,4S.     

Identification of synthetic phosphatidylserine translocases from a combinatorial library prepared by directed split-and-pool synthesis

Simple sulfonamide and amide derivatives of tris(2-aminoethyl)amine (Tren) are known to promote the translocation or flip-flop of phosphatidylcholine, but not phosphatidylserine, across bilayer membranes. This paper describes the synthesis of a 300-member, spatially encoded library of Tren derivatives with appended peptide--sulfonamide and peptide--urea arms. The library was synthesized using the Encore method with SynPhase lanterns as the solid support. A high-throughput assay was developed to screen individual members of the library for an ability to translocate a fluorescent NBD derivative of phosphatidylserine across vesicle membranes. Several lead compounds were identified, and one was synthesized independently to confirm its high phosphatidylserine translocation activity.     

Enantioselective crystal growth of leucine on a self-assembled monolayer with covalently attached leucine molecules

Enantioselective crystal growth of leucine occurs on a solid surface modified with a self-assembled monolayer depending on the chirality of the enantiomer attached, as evidenced by the X-ray diffraction method.     

Steric and magnetic asymmetry distinguished by encapsulation

Guests in an achiral cavity experience asymmetric magnetic environments induced by chiral centers outside the cavity.     

A new series of estrogen receptor modulators: effect of alkyl substituents on receptor-binding affinity

New types of selective estrogen receptor modulators (SERMs) were synthesized and evaluated for their binding affinity and biological effect on reproductive cells. A proposed lead structure (B) was derivatized to provide compounds 30 and 44, which showed good estrogen-receptor binding affinity (K(i) values: 6.3 and 10 nM, respectively), as well as minimal impact on mammary and uterine carcinoma cells. Introduction of an alkyl group in the core structure considerably enhanced receptor-binding affinity of the compounds tested. Synthesis and structure-activity relationships of these compounds are described.     

Electrical resistance of a monatomic step on a crystal surface

We have succeeded in measuring the resistance across a single atomic step through a monatomic-layer metal on a crystal surface, Si(111)(sqrt[3]xsqrt[3])-Ag, using three independent methods, which yielded consistent values of the resistance. Two of the methods were direct measurements with monolithic microscopic four-point probes and four-tip scanning tunneling microscope probes. The third method was the analysis of electron standing waves near step edges, combined with the Landauer formula for 2D conductors. The conductivity across a monatomic step was determined to be about 5 x 10(3) Omega(-1) m(-1). Electron transport across an atomic step is modeled as a tunneling process through an energy-barrier height approximately equal to the work function.     

Imaging phase separation near the Mott boundary of the correlated organic superconductors kappa-(BEDT-TTF)2X

Electronic phase separation consisting of the metallic and insulating domains with 50-100 microm in diameter is found in the organic Mott system kappa-[(h8-BEDT-TTF)(1-x)(d8-BEDT-TTF)x]2Cu[N(CN)2]Br by means of scanning microregion infrared spectroscopy using the synchrotron radiation. The phase separation appears below the critical end temperature 35-40 K of the first-order Mott transition. The observation of the macroscopic size of the domains indicates a different class of the intrinsic electronic inhomogeneity from the nanoscale one reported in the inorganic Mott systems such as high-Tc copper and manganese oxides.     

Calculating the gravitational self-force in Schwarzschild spacetime

We present a practical method for calculating the local gravitational self-force (often called "radiation-reaction force") for a pointlike particle orbiting a Schwarzschild black hole. This is an implementation of the method of mode-sum regularization, in which one first calculates the (finite) contribution to the force due to each individual multipole mode of the perturbation, and then applies a certain regularization procedure to the mode sum. Here we give the values of all the "regularization parameters" required for implementing this regularization procedure, for any geodesic orbit in Schwarzschild spacetime.     

Practical asymmetric synthesis of the herbicide (S)-indanofan via lipase-catalyzed kinetic resolution of a diol and stereoselective acid-catalyzed hydrolysis of a chiral epoxide

Racemic indanofan [(+/-)-1] was efficiently converted to enantiopure (S)-indanofan [(S)-1] by a combination of enzymatic resolution and chemical inversion techniques. An additional important technique is the use of an o-xylene complex of a hemiketal (S)-3c as a precursor, which can be quantitatively converted to (S)-indanofan and easily purified by recrystallization from o-xylene.