An Efficient Synthesis of [(Tosylamino)alkyl]naphthalenols by Nucleophilic Addition of Naphthalen‐2‐ol with N‐Tosyl Imines Using Boron Trifluoride Etherate as Catalyst

[(Tosylamino)alkyl]naphthalenols have efficiently been synthesized by nucleophilic addition of naphthalen‐2‐ol with N‐tosyl imines (derived from both aromatic and aliphatic aldehydes) in the presence of BF₃?OEt₂ as a catalyst at room temperature. The products are formed within 5–9 h in high yields (72–91%).     

Total synthesis of (+)-erogorgiaene using lithiation-borylation methodology, and stereoselective synthesis of each of its diastereoisomers

A short (8 steps) synthesis of (+)-erogorgiaene in 44% overall yield from p-methylacetophenone is described. Key steps include lithiation/borylation-protodeboronation to build up the molecule and control the stereochemistry at C1 and C4. The C11 stereochemistry was similarly set up by using lithiation/borylation methodology. The use of a mixed, unhindered borane in the lithiation/borylation reaction proved critical to success in the reaction of the tetralone-derived carbamate to control the C4 stereochemistry. The power of the reagent controlled methodology is illustrated in the stereocontrolled synthesis of all of the diastereomers of (+)-erogorgiaene.     

Geometry and quadratic nonlinearity of charge transfer complexes in solution: a theoretical study

In this paper, we have computed the quadratic nonlinear optical (NLO) properties of a class of weak charge transfer (CT) complexes. These weak complexes are formed when the methyl substituted benzenes (donors) are added to strong acceptors like chloranil (CHL) or di-chloro-di-cyano benzoquinone (DDQ) in chloroform or in dichloromethane. The formation of such complexes is manifested by the presence of a broad absorption maximum in the visible range of the spectrum where neither the donor nor the acceptor absorbs. The appearance of this visible band is due to CT interactions, which result in strong NLO responses. We have employed the semiempirical intermediate neglect of differential overlap (INDO∕S) Hamiltonian to calculate the energy levels of these CT complexes using single and double configuration interaction (SDCI). The solvent effects are taken into account by using the self-consistent reaction field (SCRF) scheme. The geometry of the complex is obtained by exploring different relative molecular geometries by rotating the acceptor with respect to the fixed donor about three different axes. The theoretical geometry that best fits the experimental energy gaps, β(HRS) and macroscopic depolarization ratios is taken to be the most probable geometry of the complex. Our studies show that the most probable geometry of these complexes in solution is the parallel displaced structure with a significant twist in some cases.     

HPLC-FLD for the simultaneous determination of primary and secondary amino acids from complex biological sample by pre-column derivatization

A rapid, sensitive, and reproducible pre-column derivatisation procedure has been established for the simultaneous determination of 20 amino acids by high-performance liquid chromatography using fluorescence detection. The amino acids were derivatized using o-phthalaldehyde and 9-fluorenylmethyl-chloroformate reagents. The optimal conditions for simultaneous separation and detection of both primary and secondary amino acids were investigated. The developed method has several advantages, namely automated pre-column derivatization, short analysis time with optimal separation, a simple and economical mobile phase, high level of precision for peak area and retention time, and higher sensitivity with more reliability of peak identification. The biological media development is the key parameter for macromolecule drug discovery. Biological media amino acids in three consecutive discovery batches were determined and the results showed a good agreement with hypothetical value. The method appears suitable for application to measure biological media amino acids at various stages of macromolecule drug discovery.     

Synthesis of novel benzo[h][1,6]naphthyridine derivatives from 4-aminoquinoline and cyclic β-ketoester

This paper describes the synthesis of 2,8-dichloroquinolin-4-amine 4 and 4,5,7-trichloro-3-(2-chloroethyl)-2-methylbenzo[h][1,6]naphthyridine 8 as novel class of building blocks. Also describes the regioselective S_NAr reactions of 2,4,8-trichloroquinoline 2 on C₂ and C₄ positions with azide, similarly S_NAr reactions of benzo[h][1,6]naphthyridine 8 at C₄, C₅ positions, and S_N2 reactions on C₃-(2-chloroethyl) side chain with nucleophiles such as primary aromatic amines, methoxide/ethoxide, and azide at different temperatures.     

1,3‐Di‐n‐butylimidazolium tribromide‐mediated chemoselective oxidative cyclization of benzothiazoyl carbaimides: A novel approach toward the synthesis of N‐bis‐benzothiazole derivatives

4‐(N,N‐Dimethylamino)pyridine is found to be an efficient catalyst for the synthesis of benzothiazoyl carbaimide derivatives using 2‐aminobenzothiazoles and phenylisothiocyanates, which on treatment with ionic liquid [bbim][Br₃] at 70°C afforded exclusive formation of N‐bis‐benzothiazole derivatives in good yield. J. Heterocyclic Chem., (2012).     

Arithmetically Cohen–Macaulay bundles on complete intersection varieties of sufficiently high multidegree

Recently it has been proved that any arithmetically Cohen–Macaulay (ACM) bundle of rank two on a general, smooth hypersurface of degree at least three and dimension at least four is a sum of line bundles. When the dimension of the hypersurface is three, a similar result is true provided the degree of the hypersurface is at least six. We extend these results to complete intersection subvarieties by proving that any ACM bundle of rank two on a general, smooth complete intersection subvariety of sufficiently high multi-degree and dimension at least four splits. We also obtain partial results in the case of threefolds.     

Reexamination of the structure of MoO(O2)2(H2O)(hmpa), hmpa=hexamethylphosphoramide by crystallographic and theoretical means

The crystal structure of MoO(O₂)₂(H₂O)(hmpa), hmpa=hexamethylphosphoramide, has been reassessed and corrected as one of the axial parameters (namely the c-axis) was reported incorrectly. This resulted in significant differences in the internal geometry of the molecule, notably an decreased O–O atom distance (≈0.03 Å) in the metal-bonded peroxo ligands. Crystal packing forces and a flat bending potential of the Mo–O–P angle accounts for discrepancies between theory and experimental structures.