An efficient method for the synthesis of quinoxaline derivatives catalyzed by titanium silicate-1

Research on Chemical Intermediates - A series of quinoxaline derivatives were efficiently synthesized by convenient and simple procedure in excellent yields using 1 wt.% of titanium silicate (TS-1)...     

First synthesis of 1,3-oxaselenepanes

The first synthesis of 1,3-oxaselenepane derivatives by the reaction of aryl isoselenocyanates with 4-bromobutanol in the presence of sodium hydride in THF as a one-pot reaction is described. The Z/E isomerism for the exocyclic carbon-nitrogen double bond in the selenium heterocycles was observed for the first time.     

A convenient synthesis of the enantiomerically pure (S)-2,4-dihydroxybutyl-4-hydroxybenzoate using hydrolytic kinetic resolution

(S)-2,4-Dihydroxybutyl-4-hydroxybenzoate was prepared in an extremely simple and practical way with high enantiomeric excess (99% ee) using Jacobsen’s Hydrolytic Kinetic Resolution technique as a key step and source of chirality.     

Fast gradient descent method for Mean-CVaR optimization

We propose an iterative gradient descent algorithm for solving scenario-based Mean-CVaR portfolio selection problem. The algorithm is fast and does not require any LP solver. It also has efficiency advantage over the LP approach for large scenario size.     

First regioselective iodocyclization of O-allylselenocarbamates

4-Alkyl-2-imino-1,3-oxaselenolanes were prepared in good yields with high regioselectivity under mild conditions by the reaction of selenocarbamates with I₂ or NIS. The resulting 4-alkyl-2-imino-1,3-oxaselenolanes on dehydrohalogenation gave 4-alkylidene-2-imino-1,3-oxaselenolanes. The formation of the (Z)- or (E)-isomer of 4-alkylidene-2-imino-1,3-oxaselenolanes, strongly depends on the configuration of the double bond of O-allylselenocarbamates.     

Synthesis of novel selenapenams, selenacephems, and selenazepines using a 2-(trimethylsilyl)ethyl protection approach

Selenapenams, selenacephems, and selenazepines were synthesized using a 2-(trimethylsilyl)ethyl (TSE) protection approach in an extremely simple way. TSE protection for selenium is used for the first time in the synthesis of selenium-containing beta-lactam. Novel intramolecular cycloaddition reaction of selenium with alkynes and allenes is used in the present synthesis.     

Pictet‐spengler cyclization in room temperature ionic liquid: A convenient access to tetrahydro β‐carbolines

1,2,3,4‐Tetrahydro‐β‐carbolines have been synthesized in moderate to good yields in short reaction time using the ionic liquid [bbim] BF₄ as reaction medium and promoter. There was no need for the use of an additional catalyst normally employed in Pictet‐Spengler condensation.     

Inverse conic programming with applications

Linear programming duality yields efficient algorithms for solving inverse linear programs. We show that special classes of conic programs admit a similar duality and, as a consequence, establish that the corresponding inverse programs are efficiently solvable. We discuss applications of inverse conic programming in portfolio optimization and utility function identification.     

First iodocyclization reaction of allene–thioureas: an efficient approach to bicyclic β-lactams

The regioselective iodocyclization reaction of allene–thioureas is described, for the first time, for the synthesis of bicyclic β-lactams. The substitution at the allenyl part heavily influenced the iodocyclization reaction. The iodocyclization reaction of the unsubstituted allene–thioureas afforded six-membered 3-thia-1-dethiacephems whereas, the substituted allene–thiourea afforded seven-membered thiazepines along with five-membered isopenams.     

Synthesis of 2-selenoxoperhydro-1,3-selenazin-4-ones via diselenocarbamate intermediates

The reactions of the diselenocarbamates, generated from isoselenocyanates and sodium hydroselenide, with acryloyl chlorides afforded 2-selenoxoperhydro-1,3-selenazin-4-ones. The structure of the product was confirmed by X-ray diffraction analysis.